Couple of things:
1) New cars are generally not a good idea, since the largest hit to a car's value occurs when you drive it off the lot. In other words, dealer mark-up is huge.
2) Leasing is generally not a good idea. If you pay $200/month for four years, that's nearly $9000. At the end of that four years, you don't own anything. You'd be much better off spending 9k initially and then selling the car for however much it's worth (6k?) at the end of the 4 years.
3) Avoid "certified" used("pre-owned") cars. Basically this is just a way to get you to pay dealer mark-up on a used car. You'll get the best bang for your buck buying used from a private party.
4) When buying from a private party, look for a vehicle with fewer than 60k miles on it. Ask things like, "How often did you change the oil?" and "Where did you have it serviced?". If the person did their own service, ask to see receipts/records. At the very least they should have notes on when they changed the oil, inspected the brakes, etc. It's also a good idea to have the car inspected by a mechanic. Most private sellers are pretty good about this (but you are expected to pay for it). If they refuse, look elsewhere. Also, always ask for the VIN and run a CARFAX.