I am a makeup artist, I don't think you are necessarily gay for enjoying that. I've made up some very straight guys who were just curious how they would look. The best way would be to ask a girl who is hugely into makeup and needs to practice. Have fun! :D
If you are really up for this, you can ask your girlfriends.. "If I'm a gay, can you give me the prettiest makeover?" That question is the easiest and will kind of excite them to have you a makeover. It'll be fun, I guess.
Depending on where you live you can get a make over done by Mac, or many dept. stores. If you're in a suburb or small city good luck! But if you're in say San Francisco ( or NY, CA...) there are lots of places to go have your make up done.
I wish i could get made over to a girl with the clothes the make up the hair relay any thing girls get to wear or put on i want to experience it i to want to be a girl and i want to be able to understand what it takes so i know how it is to be a girl.