This applies to what I've done to any car I've owned (these are the most common problems you'll have, pretty much in this order) :
Put WD 40 EVERYWHERE that moves or is an electrical connection; except brake rotors and pulleys.
Silicone spray (armor all or any cheapo stuff - if it says tire shine, it's silicone emulsion) to every rubber part, pulley or plastic stuff around the car.
Changed oil (semi or synthetic 20w50; it's hot in this area)
Added leak seal in oil (stops leaks in valve seals and smoke in tail pipe great)
Added slick 50 to your oil (extends life of the engine, consumes less oil, consumes less fuel, lowers operating temperature; my opinion)
Changed Spark plugs (platinum 2 tip - saves some gas)
Changed spark plug cables (also distributor cap and rotor if needed or wanted) if your car stutters on and off, it is probably these cables.
Installed free flow air filter (a piece of cotton rag across an empty air filter does the trick too) (saves gas, more horsepower; you choose. I prefer to ease on the pedal and save gas).
Remember to check:
Oil level (carry 1 bottle of oil to replenish)
As someone else said before me, CHECK THE DIFFERENTIAL FLUID!!. It cost me a big headache, a ton of head scratching and a new differential (400 dollars and a whole week dismounting and mounting the spare I bought) That considered, I bought a whole automatic transmission that comes with the differential in it.
If you want to save yourself some trouble, break your piggy bank before your used car strands you somewhere (an ounce of prevention is WAYYYYYYY better than a ton of cure).
This car left me stranded only once. It was due to a faulty starter solenoid (did not know at the time you could tap it and it would work again, at least until you change it)