Check for leaks NOW -- find them BEFORE a rainstorm in the middle of a cold night!
Buy a set of jumper cables; you'll thank me the first time you use them!
Get a basic set of tools, better quality is best. The more you can repair the more money you will keep in your pocket later.
Check your fuel lines, hoses, and belts. If any look cracked or worn, replace them now. Replacing things on the road is not fun! It's much better to be able to work on something in a controlled environment, on your time.
Check all the fluids; change any that look suspect. Oil is cheap compared to an engine. When you flush the radiator, be sure to run the coach heater; as you will want to flush that heater core so to keep it working as it should.
Make sure you get a good patch kit, and a small 12-volt DC powered air compressor, along with an air gauge. While you're at it, make sure you have a flashlight or headlamp, as the one time you don't is the one time you will have a flat in the dark. Besides, the headlamp will come in handy anytime you are working in low light, as you'll need both hands to work with.
Next, check the condition and air pressure of your spare, as it sucks to have a flat, but it sucks way more to have one and only then find out that your spare is also flat.
Make sure you check the lug nuts with your wrench, as many shops put on new tires with air guns set too high, making it impossible to remove them without a better lug wrench and/or cheater bar. This is also when you will find out if you have locking lug nuts; if you do, make sure you keep the "key" for them, and don't let a tire shop forget to give it back to you!
In your case, you might need a torque multiplier to remove those tires on that RV.
Also make sure you know where your jack is, where it goes, and try it out. You want to make sure you are ready and able to change a tire BEFORE you have to!
Consider changing the locks on the outer bins if you keep anything valuable in them, as most RVs use the same CH751 key.
Make sure you test out every system to make sure it works as it should. -- Read up on your rig, watch videos on YouTube, see what there is to look out for based on the experience of others, using your type of RV.
Try to save up as much of an emergency fund as you can. $1000 is a good start, $5000 is much better.
Check out what it costs to tow your RV; I know it's not something that you want to think about, but you need to. If you can't cover that, and the repair, if things go really sideways your new home could end up in an impound yard; I've seen it happen several times...