You can improve your credit rating by getting a secured credit card.
A secured credit card is a credit card where you put a deposit and then use the credit card like a regular credit card and then you continue to make payments on the credit card debt you incur.
If you keep paying the credit card back then your credit rating will eventually improve.
Also if you need a car or can afford to get one. Look at a used car lot that will let you buy a car with bad credit and a small down payment.
A friend of mine was able to get a used car through a used car dealership with her bad credit and only had to put $500.00 as a down payment for the car and they approved her for the car and by the time she had the car paid off her credit rating improved.