If you are on Facebook as your male self and not out to the world as a crossdresser, I would suggest not trying to have a Facebook account as a "female". Facebook will eventually relate the two accounts and your friends who don't know about your crossdressing are likely to get suggestions that they may know your female self. And they will see photos of your female self.
As for "friends" on Facebook, it's best to deny friend requests from people you don't actually know. There are a lot of fake Facebook accounts (your female account would be considered a "fake" account) and there is no prize for having the most "friends".
