We have been talking about getting rid of DH's horrible, horrible car and instead getting a nice commuter car with good gas mileage for me as I drive to work and DH takes the train. We already have an SUV. We want to buy a used car for many reasons. The issue is that neither of us have ever purchased a used car and have no idea what the best way is to go about this. We're both horrible at negotiating so I fear we're going to spend way too much on a lemon!

Any tips for buying a used car? Go to a dealer or someplace like Carmax?

Anyone have any suggestions on a good commuter car that is big enough for 2 car seats and gets good gas mileage? We want to stay under $20k. We're thinking of a Nissan Altima or a Ford Fusion currently.