just talk to her like a normal human lol
as a lesbian, i also get really shy, but because i am also a woman i def have experience talking to other girls. all im saying is that i kind of understand me who struggle with this.
first piece of advise from me is to just be respectful and sort of playful. i promise you most girls dont like that nonchalant stuff, but everyones different. try to match their energy!
i would also say you shouldnt make jokes about their appearance and other things they struggle with. i see this is a common thing guys do, from my experience. also dont start talking to them just because you expect a relationship! really try to get to know her and become friends and maybe then try advancing if you feel like its the right move