If possible pay as much as you can in cash, you'll save thousands on finance charges. Opt for the shortest term loan possible this will help you get a lower interest rate and will save considerably on finance charges. figure out what you are willing/able to pay monthly and hit that mark.
Go to your bank/credit union first to get a rate quote on a loan or to get a pre-approved loan before getting financing from the dealer. You may be able to get a better rate, so it is worth shopping around for the cheapest loan before you even go to the dealer.
Consider the dollar difference between low-rate financing and a lower sale price. Getting zero or low-rate financing from a dealer may disqualify you from a possible rebate.
Make sure to do your own calculations, the dealer will try to make it seem like you are paying less for you car, but make sure to run the numbers on your own. Compare the LIFETIME cost of the vehicle with various loan options to see which option is a better deal.