The simplest way is to pay all of your bills, on time, every month. For example, being late--even by a minute--will cause your interest rates to rise on your credit card (and, if you have universal default clauses, will make the rates on other cards rise). Second, try to use less than 30% of your available credit. In other words, say that--if you add together all of the credit limits of all your credit cards--your available credit totals $10000. Don't put more than $3000 (30% of $10000) on your credit cards. If you use too much of your available credit, it looks like you can't manage your money well. Don't make credit lenders think you're living beyond your means.