Credit Advice

You didn't didn't say how low your score is but you are on the right track. Keep paying down your credit card and apply for another credit card, try one of the student cards from a bank that offers them. You have a short credit history due to your age but that will improve with time. Having low credit card utilization on 2 or 3 credit cards and an installment loan such as you car loan will help improve your score. Just make sure you keep the balances low on those credit cards. High utilization will kill your credit score.

Having credit cards for several years (known as average age of tradelines, or oldest tradelines, on credit reports) will help raise your score immensely. The reason this helps is because it helps lenders know that you have a history of making payments on time, and that you can be trusted to pay back larger and larger sums.

Delta98's advice is right on - keep making your payments on time, apply for a credit card that you can use to make small, simple purchases each month and your credit score will improve, all other things being equal.