Which course are you planning to race?
There is a lot to know and the more information you have the better.
Know your car and how to fix anything on it with non-traditional means (Think MacGyver). Prep is your best hope of finishing.
Know the course map and as many hazards as you can learn about. Focus on what needs focusing on. Use Loctite, silicone and carry extra belts among other things. In the silt beds head for high ground preferably close to shrubs where roots are deeper in the ground. Roots=traction.
If you are racing Vegas to Reno water-up a couple days leading up to the race. No beer the day before. The course is long, hot and dry. Averages are 114 degrees and 14% humidity. The first half is during the day and second at night. you need to prep for whatever section you are doing. Have what you need to get through it. If you have better vision than your second driver then you may want to race at night. The first half of the race is a little more flat and you just need to set up a good pace and keep the car in one piece. Aim for handing the car off in first place here since the second driver will start in silt and end up with hills, rocks and technical terrain. The last 120 miles is very hilly, rocky, technical and dangerous at times. There are places where you can fall off. I have seen MANY racers off the edge into places they cannot get back out of. Your navigator needs to be on-point! You can outrun your lights in V2R since it gets more hilly the second half. What else??..... Oh if you stop sweating by the end of the race you are out of water and may start seeing things that aren't there.
If you are racing Parker you are in for a rough rocky ride. Keep front shock and suspension spares in your boxes. Run tubes in your tires and don't forget the baby powder. It helps reduce pinch flats and friction heat build up. You should always have a complete CV and Axle set up available in each chase truck and the remote pit. Front arms and tie rods are good too. Always have a pit spotter looking for broken welds and bent parts when in the pit. In the last 6 years I raced we did not break any axles or arms but we did blow a front shock, bend rims and lost bolts to a CV that left us putting it back together on the course. That is where the complete axle assembly is good to have at the next pit.