The more experience they have working with kids, the better. On the day of the party, make a playlist of related music to get your subjects in the mood. For example, download Hawaiian music or reggae if you're hosting a luau. If you're hosting a western-theme party, throw on some country music. When it comes time to open the photo booth, round up the kids and get them excited about posing with their friends. If you have a photo printer, you can print the photos on site and send them home with the kids as party favors. If you don't have a photo printer, upload the pictures to a photo-sharing site and send the link to all of the parents. If you're inclined, have the pictures printed out and hand them out post-party, perhaps enclosed in thank-you notes.