I actually just filed for a name/gender change in Los Angeles County on Friday. You can find the branch closest to you by using this website:
http://www.lasuperiorcourt.org/FilingLocator/UI/filingSearch.aspxThe court you want is under the "Unlimited Civil" column. You can click on it and find out where the courthouse is and its hours of operation.
Los Angeles County also has some county specific forms that need to be submitted as well. Instead of the generic cover sheet that you can find on the California court website, LA County requires this form to be used as a cover sheet:
http://www.lasuperiorcourt.org/forms/pdf/LACIV109.pdfFor Item I, do not check the first three boxes. I estimated the time for the hearing to be 1 hour. For Item II, flip to page 3 of 4 and check "A6110 Petition for Change of Name" and circle "7" next to it if you are filing at the courthouse closest to your residence. For Item III, check "7" and fill in your address next to it. For Item IV, use the information that you found when searching for your branch location and date/sign. This takes care of your cover sheet.
You also need to submit a Name Change Criminal History Assessment, which you can find here:
http://www.lasuperiorcourt.org/forms/pdf/LACIV226.pdfInformation needed for this form is fairly basic: name, address, etc.
Checklist for the forms you will need (I'm sure you have seen this before, but it never hurts to double check):
LACIV109 (LA County's cover sheet)
LACIV226 (LA County's background check)
NC-200
NC-110
NC-210/NC-310 OR a signed affidavit on a letterhead signed by your physician
NC-220
NC-230
Be sure to have multiple copies of each form. When I filed, I had two copies of each form, but I would suggest having three copies of NC-220, since one will go to the newspaper you publish in. Speaking of which, the most inexpensive newspapers I could find for publishing a notice of name change in LA County were the El Segundo Herald, Inglewood News, Lawndale Tribune or Hawthorne Press Tribune. It costs $75 for all four weeks of publishing plus they will send you an affidavit of Proof of Publication for the County Clerk. The website is
http://www.heraldpublications.com/herald/If you need any other information, the Transgender Law Center has a fairly detailed packet that you can find here:
http://www.transgenderlawcenter.org/issues/id/id-pleaseLet me know if you have any other questions that I might be able to help with!