This is taken from the Really Awesome Trans Glossary which is found on the page I previously linked:
http://tranarchism.com/trans-basics/1. Social Etiquette 101
If you make a mistake, accept being corrected gracefully, and move on. You don't have to be terrified of accidentally offending someone. That just makes things awkward. If you make a mistake and dwell on it, that's even more awkward. Even worse is starting an argument defending ignorance or assuming you know better than someone with obviously more education and experience on an issue. Being corrected is ok, and it doesn't make you stupid or insensitive. Just learn, and move on.
Use their chosen name. A trans person's "real" name is the name they choose to identify with, and no birth assignment or bureaucratic paperwork can refute that. Often trans people cannot afford a legal name change or are not yet old enough to change their name legally. Never put their name or pronouns in quotes. It's sarcastically derogatory.
Use the pronoun that is consistent with their gender expression. A person who identifies as a certain gender, whether or not they have taken hormones or had surgery, should be referred to using the pronouns appropriate for their identity. For example, if the person wears a dress and goes by Susan, feminine pronouns are appropriate.
If you're really unsure, ask which pronoun they prefer. Don't be afraid! Simply ask, "What pronoun do you prefer?" Note that many genderqueer people use they/their/them as gender-neutral singular pronouns. Be tactful when asking about pronouns; it's pretty rude to do so without at least involving yourself a conversation first.
2. Sex and Gender 101
Gender Identity: One's actual, internal sense of being male or female, neither of these, both, etc. Everyone has a gender identity, including you. For transgender people, their birth-assigned sex and their own internal sense of gender identity do not match.
Gender Expression / Presentation: The physical manifestation of one's gender identity through clothing, hairstyle, voice, body shape, etc. (typically referred to as masculine or feminine). Most transgender people seek to make their gender expression (how they look) match their gender identity (who they are), rather than their birth-assigned sex.
Sex: The assignment and classification of people as male or female based on physical anatomy at birth.
Sexual Orientation: A person's enduring physical, romantic, emotional and/or spiritual attraction to others. Gender identity and sexual orientation are not the same. Trans people can be heterosexual, gay, lesbian, pansexual, queer, etc. just like anyone else. For example, a trans woman who is primarily attracted to other women would probably identify as lesbian.
Sex and Gender Misconceptions: Catch phrases involving "between the ears" or "between the legs" are grossly misguided. Gender is no more a "social construct" than sex is, just as sex is no more "real" than gender. If anything, one's gender identity that arises from self-awareness and a lifetime of social development is far more "real" than any judgment based on what that person's body was shaped like when they were an infant.
3. Trans Terminology 101
Transgender: An umbrella term for people whose gender identity differs from the sex or gender they were assigned at birth, and for those whose gender expression differs from what is culturally expected of them. The term transgender is not indicative of sexual orientation, hormonal makeup, physical anatomy, or how one is perceived in daily life.
Transsexual: Similar to transgender in that it indicates a conflict between one's gender identity and sex assigned at birth, but with implications of hormonal/surgical transition from one binary sex to the other. Unlike transgender, transsexual is not an umbrella term, as many transgender people do not identify as transsexual.
Trans: Prefix or adjective used as a simultaneous abbreviation of either transgender or transsexual, derived from the Latin word meaning "across from" or "on the other side of." Because it avoids the political connotations of both those terms, many consider trans to be the most inclusive and useful umbrella term.
Trans Woman / Trans Man: Trans woman refers to a woman of transgender experience. She might actively identify herself as trans, or she might just consider being trans part of her medical history. It is grammatically and definitionally correct to include a space between trans and woman. The same concept applies to trans man. Unless you're involved in a conversation specifically about trans issues, you should just stick with woman or man.
Transition: The complex process of leaving behind one's coercively assigned birth sex. Transition can include: coming out to one's family, friends, and/or co-workers; changing one's name and/or sex on legal documents; hormone therapy; and possibly (though not always) some form of surgery. It's best not to assume that someone will "complete" this process at any particular time.
Transphobia: Fear, discomfort, distrust, or disdain directed towards trans people or trans concepts. This word is used similarly to homophobia, xenophobia, misogyny, etc.
Cis: Prefix or adjective that means "not trans," derived from the Latin word meaning "on the same side." A cisgender person is not transgender, and a cissexual person is not transsexual. In discussions regarding trans issues, you'd differentiate between women who are trans and women who aren't by saying trans women and cis women, but this term otherwise probably won't come up. Cis is not a fake word, not a slur, and is not intended to "label" anyone; consider trans and cis neutral descriptors analogous to homo and hetero, a pair of Greek-derived prefixes used in discussing sexuality.
CAFAB and CAMAB: Acronyms meaning "coercively assigned female/male at birth." No one, whether cis or trans, gets to choose what gender they're assigned when they're born, which is what makes it coercive. In the rare cases when it's necessary to refer to the birth-assigned sex of a trans person, this is the way to do it.
Cross-dressing: The act of dressing and presenting as the "opposite" gender. One who considers this an integral part of their identity may identify as a cross-dresser. ->-bleeped-<- is an obsolete term with the same meaning. Drag queens and drag kings are cross-dressing performers who take on stylized, exaggerated gender presentations. Cross-dressing and drag are forms of gender expression and are not necessarily tied to erotic activity, nor are they indicative of one's sexual orientation. Do NOT use these terms to describe someone who has transitioned or intends to do so in the future.
4. Sex and Gender 201
The Gender Binary: A system of viewing gender as consisting solely of two categories, termed male and female, in which no other possibilities for gender or anatomy are believed to exist. This system is oppressive to anyone who defies their coercive birth assignment, but particularly those who are gender-variant or do not fit neatly into one of the two standard categories.
Binary: Used as an adjective to describe the genders female/male or woman/man. Since the binary genders are the only ones recognized by general society as being legitimate, they enjoy an (unfairly) privileged status.
Non-Binary: Preferred umbrella term for all genders other than female/male or woman/man, used as an adjective (e.g. Jesse is non-binary). Non-binary identities do fall under the "trans umbrella," but not all trans people are non-binary (e.g. Erin is a binary woman with a trans history).
Genderqueer: An identity commonly used by folks who reject the gender binary. Those who identify as genderqueer may identify as neither male nor female, may see themselves as outside of or in between the binary gender boxes, or may simply feel restricted by gender labels. Some genderqueer people do identify within the binary (e.g. "genderqueer woman"), but reject the conventions and expectations associated with that gender.
Queer: General term for identities, presentations, and sexual orientations that reject gender conventions and expectations. There's a lot of overlap between queer and trans, but not all queer people are trans, and not all trans people are queer (many trans people do in fact conform to gender norms and expectations). The word queer is still sometimes used as a hateful slur, so although many have reclaimed it from their oppressors, be careful with its use.
Heteronormative / Heteronormativity: These terms refer to the stereotypical dynamics between primarily heterosexual masculine men and primarily heterosexual feminine women.
Monosexual / Multisexual: Umbrella terms for orientations directed towards one gender (monosexual) or many genders (multisexual).
Pansexual: Open to all genders and sexualities. Sometimes the term omnisexual is used in the same manner. Pansexual is being used more and more frequently in place of bisexual as more people acknowledge that gender is not binary.
Heteroflexible: Similar to bisexual, but with a stated heterosexual preference. Commonly used to indicate that one is interested in heterosexual romance but is "flexible" when it comes to sex and/or play. The same concepts apply to homoflexible.
5. Trans Terminology 201
Sexual Reconstruction Surgery / SRS: Refers to several different surgical procedures, and is only one small part of transition. Also occasionally referred to as genital reconstruction surgery (GRS), these terms are both preferred over "sex change operation" or anything with "reassignment." Not all transgender people choose to or can afford to have SRS. Overemphasizing the importance of SRS to the transition process should be avoided.
Gender Dysphoria: Anxiety and malaise regarding one's assigned gender/sex.
Gender Identity Disorder / GID: A controversial DSM-IV diagnosis given to transgender and other gender-variant people.
Intersex: Describes a person whose natal physical sex is physically ambiguous. There are many genetic, hormonal or anatomical variations which can cause this (e.g. Klinefelter Syndrome, Adrenal Hyperplasia, or Androgen Insensitivity Syndrome). Parents and medical professionals usually assign intersex infants a sex and perform surgical operations to conform the infant's body to that assignment, but this practice has become increasingly controversial as intersex adults are speaking out against having had to undergo medical procedures which they did not consent to (and in many cases caused them mental and physical difficulties later in life).
Gender Fluid: A general term for non-binary gender identities. Overlaps with genderqueer and bigender, implying movement between different gender identities and/or presentations.
Bigender: Refers to those who feel they have both male and female sides to their personalities, often used by cross-dressers. Do not confuse this term with Two-Spirit, which is specifically associated with Native American and First Nations cultures.
Butch: An identity or presentation that leans towards masculinity. Butch can be an adjective (she's a butch woman), a verb (he went home to butch up), or a noun (they identify as a butch). Although commonly associated with masculine queer/lesbian women, it's used by many to describe a distinct gender identity and/or expression, and does not necessarily imply that one also identifies as a woman or not.
Femme: An identity or presentation that leans towards femininity. Femme can be an adjective (he's a femme boy), a verb (she feels better when she femmes up), or a noun (they're a femme). Although commonly associated with feminine lesbian/queer women, it's used by many to describe a distinct gender identity and/or expression, and does not necessarily imply that one also identifies as a woman or not.
Drag: Exaggerated, theatrical, or performative gender presentation. Although most commonly used to refer to cross-dressing performers (drag queens and drag kings), anyone of any gender can do any form of drag. Doing drag does not necessarily have anything to do with one's sex, gender identity, or orientation.
Gender->-bleeped-<-(ing): Used to describe gender expressions that "->-bleeped-<- with" gender norms and expectations.
Passing: Being perceived by others as a particular identity, gender, age, race, etc., regardless of how the individual in question identifies, e.g. passing as straight, passing as a woman, passing as a youth.
->-bleeped-<-: Refers to a cis person who fetishizes trans people.
6. Terminology to Avoid
Disclaimer: Not all terms listed in this section are necessarily bad, but they can be very degrading if used in the wrong context or directed towards the wrong person. Please try to avoid these terms and usages unless someone identifies with them and asks for them.
Problematic: ->-bleeped-<-, she-male, he-she, it, trap, hermaphrodite, T-girl, boi
Preferred: do not use these at all
These are all derogatory. "->-bleeped-<-" is a slur that has been used for decades to degrade feminine spectrum trans people; although many trans people have reclaimed it, it is still a hurtful slur to many others. "She-male" and the like are degrading terms commonly used in pornography. Although "T-girl" and "boi" are somewhat common identities, many trans people feel they imply they are not "real" women and men.
Problematic: real, bio, genetic, natural, born
Preferred: cis
Trans people are not fake, artificial, or unnatural. Their genetics have the same effect on them that cis people's do, and they're born to be who they are just as much as cis people are. Cis is also preferable to "non-trans," which would unfairly create a labeled group and an unlabeled one.
Problematic: sex change, pre-op, post-op, non-op, female-bodied, male-bodied
Preferred: do not reduce trans people to their bodyparts
Bodyparts are not the defining trait of one's identity. If you do need to talk about surgical options or techniques, be as medical and specific as possible, e.g. "Erin underwent vaginoplasty in July 2009." Be tactful and aware when asking trans people about their medical history. It's usually none of your business.
Problematic: MtF, FtM, transgenders, a transgender, a transsexual, a trans
Preferred: trans people, transgender people, trans women, trans men, women, men
The acronyms MtF and FtM are still very common, but their use is being phased out because they make it sound like someone is stuck in transition forever and define trans people by their birth assignments. Trans and its variations are adjectives, not nouns. Using them as nouns strips trans people of their identities and objectifies them. You wouldn't say "Erin is an MtF," you'd say "Erin is a woman."
Problematic: transwoman, transman, trans-woman, trans-man
Preferred: trans woman, trans man
The one-word "transwoman" or hyphenated "trans-woman" imply that trans women are a "third gender," distinct from woman. By including the space, trans is just an adjective modifying a particular type of woman, just like Asian woman or young woman or liberal woman. While some self-identify with these terms, they are not generally accepted.
7. Trans / Cis Summary
In most cases, trans and cis by themselves are sufficient descriptors. This brief summary describes the subtle differences between subcategories for when distinctions are necessary.
Transgender = umbrella term
Transsexual = describes someone who undergoes binary transition
Cisgender = umbrella term for "not transgender"
Cissexual = describes someone who does not undergo any form of transition
Transsexual usually overlaps with transgender, but there are a lot of trans people (even transitioning ones) who don't consider themselves transsexual, and there are also some gender-normative transsexual people that don't consider themselves transgender. However, the distinction between cisgender and cissexual is almost always inconsequential, unless discussing issues specific to transsexual folks that do not involve other people under the trans umbrella. When in doubt, trans and cis by themselves are the safest choices to use in a discussion regarding trans issues.