From Bankrate.com: http://www.bankrate.com/finance/c...alling.asp
There is a trade-off between getting bonuses/rewards offers from new credit card accounts and FICO score.
"New credit accounts also hurt your FICO credit score by lowering the average length of your overall credit history. The average age of all your accounts, the age of individual accounts and the length of time since you used certain accounts all contribute 15 percent to your FICO credit score. As the accounts age, and if you manage them responsibly, those new accounts will eventually boost your credit score.
So be careful with those credit card offers. While it's attractive to sign up for rewards credit cards, especially since many of them offer cash bonuses for new cardholders, do so with prudence and only when you need new credit.
"In addition to paying bills on time and keeping revolving credit balances low," Sprauve says, "the third most important thing a person can do to improve their credit is only open new accounts when necessary.""