If you've completed Steps 1 and 2, you're more than halfway to a good deal. Now you'll need some tips on how to narrow the selection of used cars and/or understand what happens at dealerships before you're in one. The vehicle's sale price -- and not the monthly payment -- is your key focus, but you'd best study up on trade-ins, financing and insurance (F&I), service contracts and all the other extras that dealers offer.