When you buy privately:

• You pay less

When you buy from a dealer:

• You don’t risk fraud – a car is guaranteed to have a clean title, you can ask and usually will be given a copy of CarFax, certain conditions have to be disclosed by law (differs by state)
• You can get help with financing – while you might not get the lowest rate, a dealer is motivated to get you financing at any cost, and they will take care of all the paperwork
• You can purchase an extended warranty (although it is possible to purchase an extended warranty on a car bought privately)
• In most situations, you don’t have to deal with registration
• You can trade your car

Assuming you have done your research, you should know what you can afford, how you want to pay for it, and what model you want. Going to a dealer not knowing anything will either end up a waste of time, or a bad decision.

Insurance: if you don’t have any – get quotes, know how much it will cost you, and have everything ready to call insurance company, pay for insurance, and have them fax proof of insurance to the dealer. If you do have insurance – make sure you have a current ID card.

Trade: have all your keys, manuals, registration and title. If you are not on the title – you can’t trade it.

Form of payment: personal check is always the best.