1. In a modeling shoot, always go prepared, such as clothing changes that you know will fit you.
2. Always take your own make-up; even if he/she has told you there will be a make-up artist there.
3. Get references as many as you can. That would include other models and/or assignments that the photographer has had.
4. Make sure that you know exactly what the shoot consist of, and never feel pressured to do anything that you do not feel comfortable doing. If nothing else go by your gut feeling.
5. Always take along enough "cash" for cab fare etc
6. There should always be a modeling agreement"release" signed before the shoot, some might prefer after. As long as you get one it should be ok.
7. Don't ever do anything that you might be sorry for later. What you do today can affect your career later down the road. "If you pose for a photo that you cannot show your family and friends, and be proud of it, it wasn't worth doing". Mainly YOU should be proud of it.
8. If you have a verbal or signed agreement on traveling expenses etc. Make sure that it is followed up on. Written is sometimes the best.