Transsexual
Hey, sweetie! EROS is an excellent site for finding great girls; HOWEVER, ya still gotta do your research because some of them are terrifyingly bad. Yikes!
Seriously, research, common sense and TER--great antidotes for the frying-pan-throwing divas out there. 
Yay! Now that you've decided to take the plunge, there are a few things to prep, especially for us versatiles and bottoms:
(1) Namely, your ass! As a bottom, you definitely need to do an enema to be clean. You won't get everything, but it'll be clean, AND have a clean scent.
(2) Shave. I don't know if other girls like this, mind this, or find it repulsive (I would). Shave your ass down there for a few days before--use baby powder to reduce inflammation. However, it may not be any big deal to most girls. But, shaving is way cleaner.
(3) If you don't already, start flossing your teeth on a daily basis. On the day of your visit, don't floss unless your gums are healthy (i.e., no bleeding).
(4) Of course, bathe! Wear comfortable clothes that make you feel sexy.
(5) Go very light on any cologne you might wear. If it's a scent she doesn't like, it'll be too light to be a turn-off. If it's a scent she likes, well, she'll have to get closer to enjoy it! Some girls might prefer no cologne at all. Why not ask her when you call?
(6) A white, unmarked envelope for tribute/donation.
(7) Be ON TIME. If you're seeing a top-quality girl, then BE ON TIME. It's o.k. to arrive early, but wait until 3-5 minutes before to make the 2nd phone call. She is probably still getting ready. If traffic is unexpectedly bad and will make you late, give her a call and tell her what is happening.
(8) Remember: you're on a date! Treat her with respect, honesty, and lots and lots of passion!
There ya go, boy--now go have a good time and report back!