I suppose they just see you like a friend... And I assume you've never had anything more than a friendship with someone...
Erm, it goes like this. You come up to a girl and ask her out. She accepts, you get her number and you agree on the details. So you meet up with her somewhere, you talk a bit, relax, then when she has to go you take her home and if she's for it you make out in front of her doorway.
^^Ofc this isn't an only option