How do you ask a girl to pose for photograph?

Just be casual about it.

If this is for a Photography assignment,and your maybe asking her to pose nude or just normally,explain to her the situation,maybe why you'd like her in the photos ect (so she doesn't think your being a perv) and just see what she says!

If worst comes to worst she could just say no thanks and then you can find someone better to work with.

Hope it helped :)

Having a drink first helps. The above response is right, be casual. If you're taking a college course and have access to a studio you should have no problem, I never have. Explain your involvement with photography and explain that you need a model and that there is no payment for it. It also helps if you can provide her with a small portfolio of pictures after the session. Good Luck.