[Menace]

Generally, this is not an easy thing to do (in the context of game overall), because she will always be extra self conscious at work. She needs the money more than she needs your dick. Best approaches, I think, are to become a regular (which you may already be), and be super indirect and casual about getting her number. Get her to write it down on a receipt? Don't give her yours, she will never use it. However, you also don't want to give out the lingerer vibe, where internally you want to ask her out, but have approach anxiety and don't do it, and instead just talk to her (I speak from experience here). Better to just make your move and find out instead of dragging it out.