Narrow your choice of car down to two or three options. Try and do this around a period when dealers are trying to woo customers.
Approach a reputed dealer close to your home stocking the car you are interested in and find out the best price he can offer with and without you taking finance from them.
Check out the dealer's financier to find out if there are any special offers on. Get the best rates off the house financier without taking the dealer discounts to reduce financing cost. See if the in-house dealer financier combination is offering something special over and above the cash discount.
Contact rival financiers and get their best rates - ask them to recommend a dealer for the car of your choice. See if that dealer is giving you a better deal.
If there are no specials on discounts, you can take a dealer from here and a financier from there to structure your package. Opt for the cheapest combination of dealer and financier.
One can never be too sure. Call two or more finance facilitators while choosing a finance scheme. Try and compare similar schemes so that you get a good idea of what you are in for. Make sure that you get the best value for your money, after all that's what consumerism is all about.