Your credit score is calculated by you paying your bills on time, and how much of the available credit you are using. There are many other factors, but the most important is to always pay your bills on time. If you do not have any credit and want to establish some, get a credit card and just buy your gas with it. Each month make sure you pay it off in full. Pay your bills on time and your credit should be established and very good. Each year you can get credit reports online, by multiple companies.