Stuff to take in your purse should include money (enough for dinner and pictures, if needed, and some extra for emergencies), extra bobby pins, breath mints/gum, lipgloss/lipstick, and extra pantyhose (if you wore some originally). A camera is an absolute necessity. You can take a video camera to record parts of prom in addition to a camera, but never do that instead. Looking back on prom, you will enjoy glancing at pictures, rather than watching a movie.
It's probably pretty much common sense, but if you take a purse, you are responsible for keeping track of it. If you go to a smaller school, it's probably not going to be a big deal to just let it sit on a table. If you attend a bigger school, don't leave it just sitting out where everyone can see it; use your date's jacket to cover it up.
