Build around one hero piece. Pick the top or the bodysuit first, then let everything else serve it. Outfits that fight each other are the ones that photograph badly. If two pieces are both trying to be the loudest thing, one of them is wrong.
Assume heat, then assume cold. Daytime is sun and dancing, and after dark a field drops fast. Mesh, fishnet and layers that pack small do both. A jacket you can tie around your waist beats a jacket you have to carry.
Check what it does when you move. Sequins and fringe are chosen for motion, not for standing still. Anything strapless is a decision you will re-make every twenty minutes, so if it is not staying up on its own, add a harness or pick a halter.
White reads brilliantly and shows everything. It photographs beautifully, it glows under UV, and it is the single most-requested festival color we get asked about. It also picks up dust, drinks and grass, so bring a backup for a multi-day event.
Glitter goes on last and comes off hardest. Cosmetic-grade only, gel over loose, and apply to clean dry skin. Oil-based shimmer transfers onto clothes, so put it on after you are dressed, not before.
Sizing runs small across the category. Most festival wear is cut for stretch rather than structure. If you are between sizes and the piece has no give, size up. If it is stretchy mesh or fishnet, stay where you are.