Know-How Exchange : Advertising/PR

What rules do we need to follow to conduct a Drawing? We want to restrict it to participants between ages 18-25 who live in New Jersey. No purchase is necessary. We have a total prize value of $500. (Five $100 gift cards.) Winners will be selected randomly. Eligible participants would complete an anonymous survey first and if they want to enter the drawing, simply provide contact information at the end of the survey.

Obviously we'll spell out clearly in the official rules who is eligible, the prizes, how winner will be selected and prizes awarded, and how to obtain list of winners.

Is there anything critical I'm missing to conduct a Drawing? Or do we need to call this a Sweepstakes?

Thanks in advance for your input.