Whatever methode is used to purchase clothing and shoes, nothing beats trying them on before buying, or if they have a good return policy, take them home and try them on and bring back whatever isn't comfortable. Clothing and shoes by different makers tend to be different sizes even though the label says they are the same size. I find this especially true woth shows. I found shoes that fit comfortable in size 8 and others that requjire from 9 to 10. Generally I can were smaller sizes if bought in Wide size, such as 9 W as it allows more room for the toes.
in tops, they quite often come in small, medium, large and Xlarge etc. some times I can come home with a large without trying it on and find it to small and other times a medium is just right and sometimes to get the fit and look I want even xtra large fits quite nicely. If you can't bring it back, it is always best to try it on. Nothing looks worse then an ill fitted top, sweater or blouse.
Pants are a little easier but you have to be familiar with the styles of cut and what works best on you. A pair that looks like you just dropped a load in the rear isn't very complimentary. Just pick a few pairs in consecutive sizes by holding them up to yourself to see what is approximately right and try on that and a smaller and larger to get it down pat and pay attention to inseam in relation to what kind of shoes or heels they will be worn with. I like a longer inseam with heals then I do in flats. Different cuts will give you an attractive butt and legs or make you look "baggy" or to tight even if marked the same size. It takes a little experimentation to find what you like best and goes over smoothly in public.
Bras should fit your anatomy, to small a cup will restrict you and to big a cup will look rumply, of course if you don't have your own and must use forms, get the size cup to fit the forms. Band width is easy, just get a band width in your chest size. Most who are on HRT will be in the A-B range for cups though some do get much bigger. If wearing forms, keep in mind that double D's and such will only draw attention you don't want, and if one is thin and trim, smaller breasts arn't a handicap and blend in better. There is no real trick to buying a bra if you know your chest size, and most born males generally do. Cup size is simply a matter of what form sizes you use or the size of your actual breasts, and if it is your first bra, an A cup will fit most or you can up the cup size if necessary. If an A is still to large you have the option of padding or not needing one anyway. I never wore one until the girls at work pulled me aside and told me it was time or they'd kick my butt.
No real advice for skirts or dresses as I don't generally wear them, they don't fit into my lifestyle very well. Jeans and sweaters are the biggest items for me and in the summer, tanks and shorts. blue jeans are my favorite all around standard, but I also have slacks for when I can afford to go out.
Terri