<prompt> Human: Im 19 and have had my credit card for about 3 months now. Its an American Express card through USAA and I have a 500 credit limit; USAA is telling me my score is 687. I mainly use the card to pay for groceries, about 50 a week, and gas for my jeep. Both of my parents have perfect credit scores and have told me to be cautious about getting a credit card but I have been financially smart, or at least I think I have been, all my life. I try to live as frugal as possible. Neither of my parts are co signed on my card. Ive never carried a balance over the month and pay off my debt within the day of using the card. Thanks everyone.  <response>: Because you have essentially no credit history.Paying if off the day you use it doesnt benefit you at all. Just pay off the statement amount every month. Also, never carry a balance. 