1. Look at cars that have been owned by one owner and deal with that owner when possible. Leased cars are usually not taken care of as well as owned cars. Watch the paper or other sources for 4-6 months to see what the sell prices are in your range.
2. Check interior. Look for wear, cuts or other problems. Look under and in everything.
3. Check under the hood. Look for leaks, worn parts like belts and hoses, check all fluid levels and for cleanness.
4. Check all maintenance records and service tickets if available.
5. Look under the car. Check for leaks, rub marks, bent parts etc. Get it on a rack if possible.
6. Check compression on each cylinder. Make sure they are within 10% of each other and within an acceptable range. If you can't do this get a mechanic too.
7. Look for digs in the body in the sunlight.
8. Check the spare tire and wheel for wear and bent or scrapped wheel.
9. Ask about the age of the battery, last service, and available warranty, etc.
10. Drive the car, check all displays, lights, air conditioner, heater and functions of all equipment. This requires you to know the car and model fairly well.
11. Add up all that you have found and deduct it from the asking price and make them an offer.
12. Be prepared to walk away if you can not come to an agreeable price. This is real hard after you have invested this much time.
13. Make sure you explore all financing options. I bought my first BMW, by paying off the owners original loan and letting him hold a lean on the car for 18 months for a single payment balance at 9%. He got rid of the payments, the car, and had money that earned 9%. I got the car, and it gave me time to sell my other car, and I had 18 months to come up with the balance.

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