Last year was my virgin year and I learned a lot, I'm sure I'll learn even more this year. here are my biggest lessons:
Bring more than just water and beer. Yes, water is very important, but in the middle of the day I found myself also wanting something with flavor and sometimes bubbles. I drank a lot of my campmate's juice squeezes, caprisuns, sodas, etc. I wound up giving away all but one can of beer that I brought.
Whenever you leave camp, make sure you have everything you might need for the next 12 hours, even if you *think* you're just leaving camp for a few minutes to get ice. Last year I left at 9am to get ice w/ $10, my bike, a 16 oz bottle of H20 and my then boyfriend. We decided his camp needed ice too, so we went to the other side of the playa and got him ice and refilled our water, then we got sidetracked visitin all sorts of fun camps on "his" side of town, then we came back to his camp to get more water, wound up "laying down" in his trailer, falling asleep, and waking up in the dark. We had to get back to "my" side of the playa and stupidly didn't have my bike light. I think we rigged up some flashlight contraptions, but it was scary, and dumb.
Those really really sparkly, cool 4 inch heel disco ball boots you got so excited to find online and paid way too much money for are no good on the playa. I looked all bad ass in my tutu and sparkly boots, made it from my van to my campmate's trailer, and wound up changing into tennis shoes and pj pants before going out that night. Now my costumes are just as much about comfort as form. That really sparkly funky scarf- i can use it as a skirt, a top, or to protect my hair or face from dust storms.