Before you hit the car lot (or the websites), you’ll want to determine what you can afford to put down and what kind of payment you can comfortably make. An often-recommended rule of thumb is that your car payment shouldn't be more than 10% of your take-home pay. You’ll also want to estimate your minimum down payment, factoring in some just-in-case money for repairs.
If this is a first-car purchase for your teen, you’ll want to get them involved in this part of the process, especially if some of the financial responsibility will be theirs. (We have more to say on this subject; you can check it out here.)
Your banker should also be able to help you calculate payments, so this might be a good time to start the auto loan conversation. Speaking of costs and repairs, you’ll need to be thinking about whether you’ll be purchasing a used vehicle vs. one that’s certified pre-owned (CPO). A CPO vehicle will cost more, but will come with extended warranties. Gap and/or service protection on your auto loan is another option — both dealers and banks offer these add-ons that are worth looking into.