these factors may destroy your credit

Closing credit cards. Since part of your score is based on the length of time certain lines of credit have been open, closing out a 10-year old credit card could take a bite out of your credit score.

Too many in-store cards. It is always a temptation at the checkout line, but signing up for a Home Depot, Macy's or any in-store credit card just to get a 10 percent or 15 percent discount may work against your FICO score.

Even if you vow to promptly pay them off, opening up several of these accounts in succession could spell trouble for your score because opening multiple lines of credit in short period of time is considered abnormal behavior by credit agencies.