Pick a good spot for servicing. Finding other crews who are servicing for like cars is good...VW guys can often form a little camp. Close to MTC out can help if cutting it close on time. High ground if it looks like rain. Level/solid. No long grass/weeds.
Cut some boards to use under your jackstands in softer ground.
Cordless impact wrenches are valuable. Make sure you have spare batteries charged up the night before.
Many cars have certain suspension bolts that like to loosen. Until you find which ones for your car, best to lay a wrench on just about all the suspension bolts both front and rear.
Have a means of bleeding brakes handy.
Even if you can't afford a high zoot radio system, take FRS radios. The team will be rolling into town and checking in. If you are tight on time for a service, the driver can tell the crew what tools and parts to have out to fix whatever is the main priority for the driver while the codriver is dealing with timecards at the MTC. Hopefully, the driver (owner/chief mechanic 25 days of the month) knows his car well enough to at least identify problems on the transit back, even if he can't diagnose them well. For teams that have dumb, arrive and drive drivers and full time (paid) mechanics, this is different, but I'm guessing you are not in that category.
Have the radio on and LISTEN for your driver! If you have a 2 meter radio and can listen to event operations while waiting for your team, you can give your driver information on his competition (maybe the guy he is driving at the limit to beat rolled on the last stage...he can back off).
Even if you don't have a radio, listen to the driver. Get your driver/codriver in the habit of making a prioritized list on the way back to service of things to check based on noises, between stage inspections, etc. (I need to get better at this.)
Keep an eye on the clock. The codriver should be barking the time remaining (with whatever "cushion" was discussed with the driver and/or crew chief).
When service is over, anticipate what's next. If you are staying in position or moving. What needs attention. What, based on the last service, is the car likely to need at the next one.
If using the driver/owner's tools, take care of them. Make sure they are covered if it starts to rain. If the jack is malfunctioning, for example, use your between service time to try to get it working, or if you recognize a tool that is needed, make a list so the dude gets it before the next rally.
NEVER allow anyone to have open alcohol in your area.
Make a phone list of all the people on the team for the weekend as well as any long distance support people who may be able to help. (Local auto parts stores and junk yards aren't a bad idea either.) Make copies and give everyone on the team this list...maybe even make it small so it fits in their wallet. Supp regs also have the emergency numbers. Make sure the crew reads the supps before they get there and has a copy in the truck in a designated location.
Know where the fire extinguishers are.
Have fun.
