Keep your balances owing really low. Keep your utilization rate as low as possible. Ideally paying your balance in full each month BEFORE you are even sent a statement. Accept all credit limit increases. This makes you seem stronger and also lowers your utilization rates. You need more than one credit card in your personal credit report. Two or three items at least, ideally. Never ever miss any payments. If you do, it may set your score back by 100 points and take you the better part of a year to rebuild it. Use all your credit cards and lines of credit every six months - even if you don't need to. Unused cards have little impact on your personal credit score - so let them out for exercise now and then.