 But going out and applying for loads of new accounts in rapid succession definitely won't help either. Lenders will wonder why you need all that credit. Plus, all those applications will put lots of new hard inquiries on your credit report, which will knock down your credit score. 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.