Intro tip from The Straight: "The key thing to remember about festival camping is it isn’t real camping. There’s no hiking up mountain trails through verdant forests—the longest walk you’ll make is from your vehicle to your campsite—so the weight of your essentials is irrelevant. Your only goal is to get as cozy as possible. Forget the inflatable camping pillows; bring the softest ones you own. And don’t bother sleeping on the ground; this is the time to haul out your most comfortable air mattress, blankets, and floor pads for maximum luxury."
Freeze bottles of water for your cooler: This has been mentioned a lot on this board so i figured I’d lead off with it. This will put a nice big chuck of ice in your cooler and help keep everything cool while not running into the problem of making stuff soggy as it melts. Any size works and what you use depends on how big your cooler is, but i typically like the 1-2 liter bottle for this. Hopefully this can save you a few trips/purchases of ice
Tarp or Canvas “Rug”: In your main sitting/living area of your campsite you can put down a tarp or a large canvas and it make walking around barefoot a little nicer as some of the areas have stiff pokey grass/pebbles & rocks. First time we did this at Bonnaroo we used tent stakes and someone ended up kicking into one at night and hurting a foot. After that i used 6″ nails and a washer which hammer down nice and flat.
Know Where East is: and setup camp/sleep in your tent accordingly. sun rises int he east and sun coming right into your face first thing in the morning can be less than pleasant especially if it had been a long night the night before. Attach a blanket or tarp to that side of your tent to block the sunlight a bit.
Get to know your neighbors: It will build a sense of community and then you guys can look after each others stuff also. Help each other if someone has forgotten something or doesn’t know how to set something up. Many good friends have been made from just a tent away.
Make sure you establish pathways between tents so no one breaks their neck tripping over an errant tent string late at night. Bring a roll of flagging tape to tie around guy lines and mark paths.
Earplugs are always needed when festival camping, as the people in the next tent over are going to be having noisy sex. Trust me on this
If you cannot bear the thought of being without your electronics for three days, a solar charger is essential equipment. The Power Traveller PowerMonkey Extreme Solar Charger ($150 at Mountain Equipment Co-op [various locations]) will recharge its battery pack in 15 hours, and has eight adapters to work with virtually any mobile device, iPad, tablet, or GPS.
As far as footwear goes, flip-flops are great for your campsite, although not ideal for dancing. You’ll be glad you have them, though, when navigating the puddle of puke someone’s thoughtfully left outside your tent flap.
Toilet paper: never be without it.
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!)
Or for those really fancy types, portable showers can keep water warm for something like seven hours at a time, some even have plug-in heaters for easy reuse. Not the most practical invention in the universe, portable showers are more commonly used by people on festival tours and the like, but that doesn’t mean campers don’t swear by them.
Plan on Getting Dirty. Likewise, you should bring extra clothes, hand sanitizer, and a few towels. You’ll probably spend some time covered in mud, and you might not have immediate access to a shower.
Check Your Tent Before You Leave Home. A small tear in your canvas or a missing tent pole can quickly ruin your trip. Set up your tent at home and spray it with a hose to make sure that it’s ready for all weather conditions.
Circle the Wagons. If you come with a group set up your tents in a circle with the openings facing the center and each other for the reasons explained in item 2, above. If you can, set up some kind of fencing around your "compound". It discourages people from wandering through and also discourages opportunistic thieves.
Tent flag: Get a flag or balloon and fly it above your tent. When you're exhausted at the end of a long day of rockin' in the sunshine, it can be a soul crushing experience to stumble around trying to find your tent among the tens of thousands in the campground.
You cannot bring enough duct tape
And for those looking for a more original "tent", there are these options: