Some things to look for:
Check if 4 wheel drive is working, front Autohubs can be problematic.
Can be a cheap fix, or may need new ones.
Wet carpets passenger and driver's foot well. also around rear door seal.
Rock the car side to side from the open driver's roof side, listen for clicks and clunks. Could be drop links on antiroll bar, cheap to fix.
Oil leaks check bottom of bell housing, prop shaft seals engine around the oil filter and down the back of the rocker box cover.
Look at rear brake backing plates for signs of either brake fluid or diff oil.
Check braking, is it pulling to one side, is one disc or drum hotter than the other side after a run?
Wet a finger first just in case or you may burn yourself
Coolant fluid leaks especially around the water pump.
Check for smoke on start up, and whilst reving, note the colour..
White Could be air getting into the fuel system,some cheap fuel filters leak or fuel lines corroded.
Blue Oil burning.....
Black Might need new glow plugs, new air filter, or a damn good service.
Note: not all these issues are found on every vehicle, but are some of the common issues you would find on any car with age and mileage.
My Mav I have had 16+ years and has been the most reliable vehicle I have ever owned. That's why I keep it. :thumb2