First, know your credit score. It will range from 300 to 850, but for your score to be considered good, it generally needs to be above the high 600s. If your score is less than good, then consider waiting until you can either repair any errors on your credit report or build a more positive credit history (by making timely payments, paying down debt, etc).
Next, you should do your financing homework and research lenders. It’s best to get pre-approved for a loan before you walk into a dealership and choose a car because you’ll know the maximum price you can pay. This will allow you to be a more confident, informed negotiator. To get pre-approved, you can apply for a loan online, over the phone, or in person with the lenders of your choice. Be prepared with documents that provide proof of your ID, income, and credit history. Try to get pre-approval from at least two or three lenders, as comparison shopping is the best way to secure a good interest rate and term.