Most Helpful Girl
White if its the kind that throws paint at the crowd.
If its not just go with neon everything. It doesn't matter if the colors clash. There will most likely be black lights to make it look awesome
Pick shirts or hats with fun sayings ('sorry mom' is a popular one, you can get them in a spencers) light up accessories, necklaces, bracelets, gloves, shoes, glasses. Some places won't allow outside glow sticks but they'll have some available for purchase
Any tie dye or drug themed clothes worth well too lol
Don't worry if you don't look the best, its usually too dark to tell anyways, and everyone is more concerned with the music (plus they're probably high or drunk and won't remember/give a fuck)
Have fun :)