Figuring out what to bring to Coachella can be a doozy, especially if you've never been. If you plan on staying on the festival grounds, you'll need a tent, sleeping bags, chairs, eating utensils, and kitchen tools (if you plan on cooking). You can also camp out in your own car at the assigned sites, which you can read all about here.
Additional essentials and recommended items for attendees include a portable phone charger, sunscreen, a cooler with frozen water bottles and/or a refillable water bottle (remember: it's literally in a desert!), lots of snacks, and a portable mini fan. To better your experience, you can also bring some of your own forms of entertainment, such as card games and board games.
For personal hygiene, you may consider bringing hand sanitizer, face wipes (there's going to be dust), and toilet paper, because you shouldn't count on the porta-potties having wipes — sorry! As for the list of things you should know to bring but might forget anyway that would include your ticket, wristband, ID, and credit or debit card you used to purchase the ticket(s) with.