Storage: It all really depends on your style of raving, some people don't like to carry much at all while I prefer to always have stuff and not need it rather than need it an not have it. If you're a female and like to travel light I might recommend a fanny pack since they keep your stuff in front of you where you can likely see if someone is trying to steal your stuff. I always bring my camelbak with a spare water bottle filled up in case someone else might need water.
https://www.amazon.com/gp/product/B01DM0OJXS This is the fanny pack my wife brings and normally carries wet wipes, diffraction glasses, ear plugs, gum, chapstick, and other goodies.
Sanitation: Individually wrapped wet wipes because the "sinks" run out of soap or water and the port-o-potties have run out of toilet paper and its just all around nice to clean your hands before you eat after traded kandi with people or touching handrails and so on. We carry two different types because the ones you use for your hands aren't supposed to be used on your nether regions without burning or worse (if you're a female) https://www.amazon.com/dp/B0043D68YW is what we carry most of and between my wife and I think between 3 days of EDC, Project Z, and a couple other events I think we used maybe a box.
https://www.amazon.com/gp/product/B0121L4EZM Haven't used too many of these as port-o-potties can be nasty as hell but if you can't hold out till the end of the night or are camping this is likely your only choice as I mentioned sometimes they run out of toilet paper or if you or any females in your group have lady issues.
Safety: Ear plugs for sure it doesn't matter if they're the neon disposable ones or reusable. We all like to feel that bass but sometimes it gets hella loud and it hurts. Not to mention you want to be able to continue to rave for years to come without damage to your hearing. https://www.amazon.com/gp/product/B00A3Z44RM these are what we have and they work well without impacting the sound quality as much as say the foam plugs. At first I thought security would shit themselves as its technically in a pill case but I'm just straight up with them and they're cool.
THANK YOU! I actually ordered a pair of Downbeats from a friend's recommendation! I'd like to share the link here to advocate for ear protection. I too have been to a lot of concerts and yes, they are loud, and what is worse, you'll end up being loud too, losing your voice and stuff. Be mindful of concert-goers round you too and their ears.
DownBeats Reusable High Fidelity Hearing Protection: Ear Plugs for Concerts, Music, and Musicians