Regardless of whether you decide to buy or lease your next car, establishing a realistic monthly payment that will fit into your budget is a crucial first step. How much should this be?

A rule of thumb is your total monthly car payments — whether you own one car or more than one — shouldn't exceed 20 percent of your monthly take-home pay.

Check the Edmunds.com "Financial Calculators" to help you estimate what your monthly payment will be based on purchase price, down payment, interest rate and length of loan. Take the time to run the numbers now, before you go car shopping, print out the result and put this information into your car-buying folder. It will not only show you what you can afford, it will also help you control the numbers when you negotiate with a car salesman.