You can use photography to flirt with women. Showing your photos or asking them if they'd be interested in doing some modeling is a perfectly fine way to break the ice. HOWEVER, never flirt with someone while you're getting paid to photograph them, or while you're paying them to be your model. Hitting on someone while they're on the job and can't necessarily reject you, is sleazy, creepy, and will ruin your reputation. Additionally, never touch a model without their permission, and never have a model shoot nude/revealing shit without their prior agreement. Pressuring them to do so the day of the shoot is again, sleazy, unprofessional, and will ruin your career.
Also, you can and should make comments about how the model is doing wonderful, they look amazing, etc., but DO NOT make comments about their bodies that you wouldn't say to your mother. You're there to get paid, so be professional and make them look and feel amazing.