Fluids: You're gonna get some on ya.
Short list of what you should have one hand: CA Glue. Extra shock fluid. Extra diff fluid. Motor cleaner. SXT 3.0 tire sauce. Something to drink that IS NOT THOSE THINGS.
Your real car is full of fluids. Radiator fluid, brake fluid, oil, gasoline, transmission fluid, bearing grease, windshield washer fluid, and sometimes a few others. Well, little race cars have a bunch of their own fluids too.
Most of the fluids you're going to use, are silicone oils. Shock oil, diff oil, many of the greases, are all silicone base. Sounds bad, but if you use shampoo, you're touching that stuff nearly on a daily (I hope it's at least every couple days..) basis.
So shock oil, diff oil, both are likely to come with your car. And you'll note they're always double or even triple bagged. There is good reason for that.
This stuff does not dry, does not polymerize, does not get old, or get bad. It's also going to suck straight through any gap in any lid of any container. I'm emphasizing this because once silicone gets on stuff, it's hard to get out.
Cleanup, is with dishwashing liquid, or alcohol. At least, if you want to actually get rid of it. You should store them in a plastic bag, or plastic tub, so any leaks are contained. Trust us on this one, you don't want to try to clean up 2oz of $8 shock fluid once it's soaked into your gear bag.
There are other fluids you're going to want. Alcohol, is useful, for cleanup. Also superglue, or CA or CyA, or cyanoacralyte.
CA is used to gluing tires onto the car. For building up differentials. CA is the stuff of nightmares, but can be dissolved using acetone, so don't tear your skin off if you do get stuck..
CA Accelerator: (also known as kicker) this is a spray used to make puddles or open CA harden. It's common to buy both the CA and Accelerator in the same package. While the glue is essential, the accelerator isn't.
CA is very useful at the track for tuning your tires, or assembling new sets of tires. It can also save your car, if you split a deck open, or have other trouble with your car.
Motor spray: This is a spray cleaner that originally was used to cleaning out electric motors, but is the best thing for removing smudges, rubs, and other hard to deal with crap that's picked up on your car. It dissolves tire gunk, allowing you to clean your tires of stuff it's picked up off the track.
"Sauce". Tire sauce is used to get your car tires "working" on the track. When your tires are cold, or raw, they're not very sticky, and the car will be hard to control. And while hard to control it's also not building up temperature in the tires. Tire sauce gets you through that first lap or two, so you can get your tires warm, and working.
We only use SXT 3.0 at our track. This is for your comfort, and the comfort of others.
Water: Drink lots. If you're not drinking, you're not going to be performing your best. So.. drink.