How would i ask her out?

There this girl I've known for about 3 years we are friends. I never really been interested in her but i been dating a lot of women and nothing ever works out so i thought hey me and her get along very well why not ask her out and see how it goes. we have done a lil touching in vegas when we was both drunk when she found out that we did that it was so awkward for a lil while i don't know if that helps. But anyway how would i go about this cus if she says no it will probably be awkward for a while.