"A good way to improve your score is to eliminate nuisance balances," says John Ulzheimer, president of consumer education for SmartCredit.com. Those are the small balances you have on a number of credit cards.

The reason this strategy can help your score: One of the items your score considers is just how many of your cards have balances, says Ulzheimer.

So charging $50 on one card and $30 on another, instead of using the same card (preferably one with a good interest rate), can hurt your score, he says.

The solution to improve your credit score: Gather up all those credit cards on which you have small balances and pay them off, Ulzheimer says. Then select one or two go-to cards that you can use for everything.

"That way, you're not polluting your credit report with a lot of balances," he says.