Here are four tips from "The Summer Camp Handbook" by Jon C. Malinowski and Christopher Thurber.
1. Label everything. We can't say this enough, so we'll keep saying it. Label everything.
Avoid homesickness!
2. Make a list of everything that you're bringing to camp and tape it to the inside of your trunk or suitcase. If you're packing into a backpack or duffel bag, put that list in one of the pockets. Use the list at the end of camp to make sure you haven't forgotten anything!
Send your kid to camp!
3. Instead of stacking neatly folded clothes in your trunk or suitcase, roll the clothes neatly and pack them upright like pencils in a jar.
That way, you can see everything that you have, without unpacking a thing!
4. Pack small items in zippered plastic bags so they all stay put.