Once you are armed with your report you are now ready to go shopping. You will be in a position to ask for a good rate and the dealership can't argue with your new proof. By just having a good credit report you can easily obtain a $15,000 car loan with a low interest rate, maybe even zero percent, versus a customer with a bad credit score that will only be offered upwards of 10% or more.
Before shopping in person, go shopping over the internet; see what the options are for applying online for a loan. Sometimes it is certainly faster to apply online instead of at the dealership. This can save you many hours. You may be able to secure a loan at a much cheaper rate than the dealership would be prepared to give you. Shopping online can prove to be a good hassle free experience and can be done on your own schedule.
If you have qualified for a loan the sales rep at the dealership will view you as a cash buying customer which puts you into a good negotiating position. You can hold the upper hand.
Look at your options for buying new versus a used vehicle. Other than just price, think about the warranty options. Many times new vehicles have lower interest rates, so your monthly payment may not be that much different and could prove just to be as affordable. Consider repairs and maintenance when purchasing used, it may be worth getting the new car! A new set of tires can cost you upward of $500, so if the car you are looking at has tires that need to be replaced, think about putting that money into your new payment.
Rushing into any purchase is of course never recommended. Take the time to do your due diligence and research and your shopping experience will be a positive one.