I drive a ~550mi round trip fairly regularly. Once a month give or take. Generally I'll just give a check over for tire pressures, fluids, leaks. But that being said I do my own maintenance and have a good idea where everything else is from memory. Nothing is more than 100-150 hours/3-3.5kmmi of run time since I last laid hands on it (my own service intervals)
If you're not sure: Here's a good list
Rack it up, give a shakedown. Check for freeplay in wheel bearings, steering components, torque wheels and wheel bearings.
Check brake pads, calipers, hoses, brake fluid, e-brake actuation
Check tire pressure incl. spare. Check for foreign objects
Double check engine oil, p/s, trans, coolant, diff fluids, t-case, condition of air filter, make sure all intake hoses are secure. Give the engine a start and listen for any peculiar noises, check oil pressure.
Verify 4wd operation if applicable
Inspect radiator, WP, hoses, heater core connections incl. rear
Check belts
Check for any fluid leaks
Check wipers if it's been a while since you've used 'em and don't know how they're doing
Verify all exterior lighting
Check heat, a/c, defroster operation
Have battery/alternator tested and verify condition of cables and visible grounds.
If you have any check engine codes, take a peek and see if it's something you need to deal with immediately.
Check alignment if you've not done so recently.
If you don't have a roadside kit, I'd suggest getting one. Mine has a multi tool, blanket, flares, reflectors, air compressor, fix a flat. I also have a jump pack with me and a fairly extensive hand-tool kit I've pieced together.
Oh, and grab a clean, dry microfiber and buff the shit out of your interior glass. You'd be surprised the scunge that builds up without realizing!
