 Don't assume you have to carry a balance month to month on your credit card to build credit. You can build credit just as effectively and much cheaper by paying the balance in full every month and avoiding finance charges altogether. Making payments on time is the single biggest factor in your credit score. And finally, don't fret if you've had some credit missteps in the past. Newer, positive information will count more and those previous events will count less as time goes along. I'm Greg McBride.