Some notes on alternative genders:
Contrary to popular belief, you can't really choose an alternative lifestyle anywhere near as much as people think you can. Usually it just sort of happens. You can't choose your gender or sexuality any more than you can choose your sex or race (although I'm sure it would be fantastic if you could choose every aspect of your personality and body).
As someone pointed out to me a while back, you can transgress gender roles and stereotypes, but you can't transgress your gender. You do what comes naturally to you, and trying to choose to act a way that doesn't resonate with your gender can not end in happiness1. The only reasons for acting like you have an alternative gender are either confusion or actually having one.
Also contrary to popular belief, sex and gender aren't necessarily related. Sure, for most people, their sex and gender are both female, or both male. This isn't always the case though, and there are more than two possibilities for either. Intersexed people, for example, have bodies that are somewhere between male and female (or both). Their minds can still be male, female or neither, making them normal men, normal women or (shock, horror) normal genderqueers.
The main problem with writing about "alternative" genders is that every language I know of lacks the proper words to explain the concepts easily, let alone name any genders other than male or female.
Some people like to picture a scale, where you have male on one side, female on the other side, and a whole spectrum of in-between genders, well, in between.
Others think even this is too simplistic and prefer picturing a sphere, with many possibilities including a complete lack of male and female, large amounts of both, or something else entirely.
Personally I think it's easier not to think about the whole thing and just present yourself as you feel is right, without trying to work out which underlying gender caused you to dress a certain way or sit with your legs crossed or apart or whatever. Life's too short to overanalyze.
1. Try a Google search for "percent transsexuals suicide" (without the quotes), for example.