1) Don't ever open a credit card just to open one (unless its your first or second). Having too many credit cards open even if they remain unused can hurt your credit score. Also, it is just a temptation to use them

2) Pay the balance off completely each month. just like payday advances, Don't take one out (or spend the money) unless you can pay it back by your next paycheck or billing cycle.

If you do manage to pay off your credit card debt, don't cancel your cards. Canceling credit cards can hurt your credit.

Call and negotiate your interest rate, you may be surprised, if you have been a good customer they may be willing to take your interest down a couple of points.

And if you are really in over your head you may want to consider debt relief or credit counseling services.