Buying a used car is a double-edged sword, as you can buy a car in excellent condition at an unbeatable price, you could find a problem with wheels that only will give you headaches and will be more expensive than a new vehicle. The result will always depend on how careful you are when checking the car before buying it.
The first step is talking to the seller. Ask them why are they selling the car, if it has been in a serious accident, if they keep the car in a garage or if it stays on the outside. Also, you can ask if they can show you the bills for the repairs they have made, when it was the last service, etc. This will allow you to inquire into the owner's habits, if it is possible that some parts have been replaced by others than the original ones, among other details. Pay attention to the seller's attitude.
Check the outside of the car, if it has bumps or scratches. Do not worry about small scratches or dents, that can serve to lower the price, and it can be repaired in a flash. Look for asymmetries in the car, because it may indicate that the car has been crashed and badly repaired. Check that the headlights, tires and everything is in perfect condition.
Lean on the trunk and release the car, so you'll check the condition of the shock absorbers. If the car bounces, the shock absorbers must be repaired. Also, check the wear of the tires, which should be even, if there is one side more worn than another, there are problems of suspension.
If you can ask a mechanic, friend or acquaintance, to go with you to check the car, so much better, because they can open the hood and check thoroughly the state of the engine. If not, check for oil leaks, look under the hood, look if it is too clean or too dirty (both ends are worrisome). Let the engine warm up a little, carefully remove the oil plug and check for smoke. Place the hand carefully, and if it generates pressure, it is a sign that the engine has a lot of wear and you do not want to buy them.
Check the boot The car should start without any problem, if there are noises or rattles, there may be some broken engine support, or fuel injection problems. Let it run for a while, turn it off and then turn it on again. It should start without any problem. Let the engine running, then turn the steering wheel from one end to the other. If there is a grunt or squeal, there may be a problem with the assistance system or the engine belts. The steering wheel should be able to turn fluidly, without making any strange noise.
Pay attention to the inside of the vehicle, check the condition of the carpet, the seats; try all the electrical parts: windows, air conditioning, sound system, windshield wipers, lights, everything should work perfectly. Take advantage and look at the knob of the speeds, pedals and the steering wheel; if they look worn out, but the car marks just a few kilometers, you shouldn't trust the seller.
If the clutch is more worn on the left side, it is because the owner supported the foot on that pedal, which causes stress on the clutch and can cause problems in the future. Those small details are the real tell-tale.