Go to Coachella as many years as I have and you get the whole packing thing down to a science. Yes, I said science, but it's not rocket science. You're obviously going to want to pack face wipes and lip balm (shit gets dirty and dry, my friends) and don't even think about forgetting your SPF or water bottle. You're an adult and can handle the essentials just fine.
But there's also the art part. After years spent crowded into tiny, overpriced hotel rooms with friends, seasons spent baking at hotel pools and weathering what I like to call The Great Coachella Dust Storm of 2014, I can tell you exactly what ancillary products you're actually going to want and what you'd wished you left at home.