You should pull your credit report here and see what's on it.
Most likely, your score is low simply due to a lack of credit history. Remember that your score does not start high, but rather begins moderately low, and rises as you show good credit and money management--paying your bills on time, for instance.
The good news here is if you don't have any major hits, like charge-offs or BKs, you should be able to significantly improve your credit score. Keep any credit card you have now, and charge just enough to get a bill. Pay that bill on time every time (autopay if you can). Open another credit card (don't pay any more than $39 for an annual fee), and do the same--charge just enough to get a bill, and pay that bill on time. About every six to nine months, bug the card companies for an increase in your credit line--higher credit limits look good. In six to nine months, get another credit card.
A year from now, you should be looking at a significant gain. You should then be around 650 to 675. When you're up to buy a car, you might want to look at financing part of it in a simple-interest loan. Save your money, and pay an extra $100 or so each month on the loan to retire it within two years or so and keep your interest payments down. A paid car note also looks good on a credit report and raises FICO.
In three or four years, there's no reason you shouldn't have a FICO well into the 700s.
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in a credit-scoring postnuclear Stone Age...