Ask her to separate her knees, use their straight arm to hide their stomach. You can also have them peek up or pull the bra straps off for variety in this pose.
Ask her to put her hands together, hair on the far side, arch her back like the yoga position called cow. Have her rock forward and back to get different variations of this pose. I like this pose best when the light is coming from behind them.
Similar pose but from a different angle. I find this shot works best at a shallow aperture, and with the top of their head cut out fo the frame. Make sure you don't see toes in the background.
Ask her to put her back up against the wall with the knee closest to you bent. For her hands you can have her run up and down their body, pulling at bra straps or pulling up on underwear