The 12 volt electrical system powers the electronic controls of your appliances, fresh water pump, TV, alarms and interior lighting.
Learn to troubleshoot and maintain your 12 volt DC electrical system including the house/auxiliary battery(s), converter charger, 12 volt system switches, fuses and wire/terminal connections. Get a cheap multi-meter an follow the directions.
RV tires go bad sitting parked, have them inspected for sidewall cracks that lead to tire failure underway. Have brakes inspected and serviced to prevent calipers from sticking, and brake fade. Have brake fluid and front brake flex lines replaced.
Have engine cooling system including water pump, clutch fan, and belts and hoses checked and serviced as needed. Practice using your mirrors changing lanes and getting to off ramps safely be aware of blind spots. Use a GPS to help plan for merges and off ramps. Be aware of RV weight and stopping distance. Have emergency road service and have a comprehensive set of tools. Park/camp where you will be safe!! There's a lot more to know but these are the basics. Lots of good "how-to" videos on You Tube.