Here's what to bring, what to avoid, and most importantly, advice on where to pee.
Money belt.
Bring a money belt, or as I see it, the "inside fanny pack" or "fanny pack diaper." Here a guy wears it on the outside to show you how loaded he is, but in reality, this would be tucked into the front of his pants. This is a common (also paranoid) tourist practice in Europe to avoid pickpockets.
Seductive...
and light-weight!
Source: travelfeeder.com
Dry Shampoo
The gods have spoken and they don't really care if your hair is dirty. They just don't want it to look dirty. I'm not sure who invented this heavenly powder, but kudos to them. If you look less gross, you'll feel less gross.
Source: mollypiper.com
Shower wipes.
A complete necessity if you're camping out on festival grounds. Chances are, you're going to start smelling. Quickly. Real showers are a thing of distant dreams, so carry shower wipes with you. Not only will you feign cleanliness, you'll feel better. And I imagine it's a good way to make friends (clean your friends!)
Source: fasttrackfundraising.com