long time desert roadfag here. CA, AZ, NM, NV, UT, etc.
Bring PAPER maps or road atlases. I'm a big fan of electronic route stuff (
rwgps.com is great for 4 wheels too) but out there you migh have phone but often NO DATA SERVICE.
Even if you stay on-road, make sure your cars are reliable. I used to do lots of jeep trail stull in my 2wd station wagon. I just went slow and picked my way through dirt, got out to pre-walk in places etc. Macho is stupid.
Really, have 2 gallons per day per person always. Most of the time this is excessive. Until every 10th time it's not. Also, newbie.
Loose long sleeves (sun, cold at night). don't burn, whitey.
Fancy gear is a waste of time. On solo trips in my 52 yr old car I bring folding cot + tarp (cold and rain protect), big old dumb sleeping bag, tin foldup table, foldup chair. One-burner coleman type stove. Plastic box with spare fork, knife, etc, liquid soap, small bucket for washing.
Skip all the fridge, icebox etc overhead: you can easily east for 2, 3, 4 days on yoghurt, canned chili, bread, salami, cheese, apples, bananas, etc. Eat fresh veggies in town. You'll be fine, far less shit to fuck with and overhead of melting ice etc. fuck all that.
Always keep tank FULL. Don't bother carrying gas, esp newbie. Every trip leg, LOOK AHEAD plan every gas stop. It becomes automatic and no big deal.
Embrace newbie. Skip the macho knowitall crap. Even experts get lazy and die from stupid. Embrace ignorance.