Here is a partial list of things to take:

Personal items
socks / shoes
sweater or sweatshirt (check weather)
2 bath towels
1 beach towel
1 jacket or raincoat (check weather)
1 pair sweat pants/long pants (check weather)
hat or sun visor
personal hygiene items
medicines
flashlight
LET US REPEAT - flashlight!
batteries for flashlight
insect repellent
sun screen
Did we mention flashlight?
Food, snacks, drinks, cooler, plates, cups, cutlery : everything you would take on a picnic
plastic bag for wet clothes
pillow(s)
blanket(s) or sleeping bag(s)
Tent
think of bringing a flashlight
Cot(s)
Lantern/lights (flashlight would be good too)
camping stove, pots/pans
Gas/propane cylinders
Fan (if electric site)
Radio/boombox
Chairs
Dishpan
oh yes... a flashlight and extra batteries... just in case we forgot to mention it.