Burning Man is an unpredictable place, full of marvelous and unexpected distractions. You may go to the porta-potties at noon and not find your way back to camp until nighttime. Consider putting together a small playa pack with all of your playa needs. Keep it close at hand when you're in camp, and carry it with you whenever you leave camp. It should probably contain:

• Lots of water. Leaving camp without plenty of water is asking for serious trouble. Water bottles work well, but a hydration pack with a drinking tube works even better. Yes, the mouthpiece will get dusty. No, you won't care.
  
  
• Food and related supplies
  • Enough food to keep you going for a while. A couple of snack bars should be plenty.
  • A mug. You never know when a stranger will offer you a strange and wonderful beverage.
  • Hand sanitizer. You never know when a stranger will offer you a strange and wonderful food. It's a good bet, though, that your hands will be dirty when it happens.
  • Pocket cutlery isn't vital, but it may come in handy.
    
    
• Environmental protection
  • Some kind of sun hat.
  • Sunscreen.
  • Lip balm.
  • Sunglasses.
  • Goggles that seal to your face (for duststorms).
  • A breathing mask (also for dust storms).
  • A keffiyah or similar scarf will come in handy for protecting your face and head against sun, wind, and dust.
    
    
• Personal supplies
  • Hand wipes have numerous uses.
  • A small amount of toilet paper. The porta-potties are usually well-stocked. Usually. Pocket tissue packs are the perfect size.
  • A small plastic trash bag. Ziplocks work great.
  • You probably won't need any safe sex supplies while you're away from camp. Probably.
  • Sugarless gum. Brushing your teeth on the playa is complicated, and doesn't always happen as often as it should.
    
    
• If there's any chance you'll be out at night:
  • A flashlight or headlamp, with extra batteries
  • Marker light(s). People without lights are darkwads. Don't be a darkwad.
  • Cold weather clothing.
    
    
• Optional, but nice to have:
  • A camera, in a sealed plastic bag. With extra batteries and media, if necessary.
  • Pen & paper. Most pens (ballpoint, sharpie, etc) cease to work in extremely dusty weather - you may find pencils more useful.
  • A small multi-tool.
    
    
• If you smoke, a portable sealed ashtray (like a film can or mints can).
  
  
• Things you probably don't need to carry:
  • Bike tools. Your bike probably won't break. If it does, walking it back to camp isn't a big deal.
  • Two-way radios. These don't work nearly as well on the playa as you think they will.
  • A GPS. You won't need it.