By Jim Donovan,

PHILADELPHIA (CBS) – Trying to clean up your credit? Well you may not realize it, but closing out a credit card can put a big dent in your credit score if you’re not careful. So 3 On Your Side Consumer Reporter Jim Donovan has some advice to minimize the damage.

30 percent of your credit score is based on what’s known as your credit utilization ratio — it’s a fancy term that describes the amount of credit you’ve used, compared to the amount you have available.

If you’re considering closing an account, credit card expert Beverly Harzog says don’t do it if it’s your only card. And if you have others, check the balances.

“Take a look at your other balances on your other credit cards. Are they fairly low? You want to get the balances as low as possible so that you have a low utilization ratio even if you close that credit card and lose that available credit,” says Harzog.

The common reasons that consumers close credit card accounts are due to new or increased fees, and high interest rates.

If you’re switching to a new card, keep the old one open until you receive the new one.

“That way your FICO score will start utilizing the new available credit with the new credit card into your FICO score, so you’ll minimize the impact a little,” according to Harzog.

It’s best to have a zero balance when closing the card. You can close it over the phone, but also follow up later in writing.

Also, after a month or so, check your credit report to make sure the account is noted as “closed.”

By the way, all consumers are entitled to receive one free credit report a year from each of the big 3 credit reporting firms, Equifax, Experian and Trans Union. To get your free copy visit: www.annualcreditreport.com.