This depends. is your friend also lesbian and/or bisexual? and how long have you guys known eachother? if you havent known eachother long then i say tell her that you are lesbian first if she doesnt already know and see what happens. if she does know then tell her straight up. and if your afriad just tell her the kind of girls you like (referring to her looks, personality etc;) and see if she catches on. if not then she either is avoid it or doesn't see what your trying to say. but if shes lesbian/ bisexual to i say ask her out. the worst she can do is say no right?