Research what other like-models in the geographical location you'll be working in are getting paid. All of the answer thus far seem to be all over the place- as are the answerers- which would indicate to me that you might want to do a bit more research on the issue if possible.
I, myself, pay models $25.00 per hour and up- depending on the look desired, the model's looks, etc.- so not every model is going to be making the same amount. If you have experience, you will probably get paid a bit more.
Regarding taking anyone with you during a shoot: this may or may NOT be a good idea. DON'T take your boyfriend or significant other as they do tend to get a bit jealous and you won't be natural in front of the photographer if you're constantly watching them to make sure they're alright with whatever you're doing. It might be a good idea to take one or two impartial friends- people you're close enough with who aren't judgmental or whom you don't need 'permission' to do whatever type of images you've been hired to do.
Always read what you're signing, and negotiate images/book(s)/etc., prior to signing the model release. It's always a good idea to have a copy of the finished work for your portfolio.
:) Good luck, be safe and have fun!