Another obvious one you’d think, but usually the easiest to forget. Basically don’t use sunscreen if you want to look like a swollen, talking tomato. At my first Bonnaroo, I fell asleep on my side under a tree without sunscreen and woke up two hours later with an incredibly painful sunburn and looking like Harvey Dent. While I no doubt looked totally badass, it was uncomfortable and could have been easily prevented. Whatever SPF you normally bring to the beach, double it.