Certainly make sure the has a parent or guardian with her - also make sure you have model release forms and stuff ready as well for the parent and girl to sign - also don't overlook sitting them down to firmly *yet kindly* outline what the outcome from the shoot is to be and what and how your going to take the planned shots and stuff. I am sure you will do all this anyway, just make sure that you don't forget anything
C.cloudwalker - something I have picked up from some shooters is that boyfriends are often not the best company for a model on a nude shoot. Several said that they had their wives or a female assistant on hand to help - since you can direct your wife/GF/assitant far easier than a stranger for positioning the model and the model in question is less likley to resist a females touch than a pervy guy with a camera