For me it started out as a way to make it easier to get guys and to be with guys. There are a lot of guys which wont do stuff with another guy, but they will do stuff with a guy dressed as a girl.
Another thing I learned is that guys are very visual. Lots guys like lingerie, garters, thigh high boots, leather and latex. Often times women will wear stuff like that but not because they want to. Enthusiasm goes a long way with guys. Having someone who is thrilled to wear whatever kinky outfit you can think of is a great turn on for a lot of guys. It isn't necessarily lingerie or bedroom wear that guys want. Married guys seem to like jeans with stiletto heels or leather pants or a sexy body con dress.
I had a lot of hang ups about doing stuff with guys when i first started out. Dressing as a girl somehow gave me a free pass on being bisexual. Once I became anally orgasmic it was game over.