The most upsetting thing about FICO scoring is that you actually lose points for not carrying a small balance. That's the stupidest thing I've ever heard! If staying out of debt means losing 7 points (which I did today) so be it!
This is not true. Carrying a balance means that your statement posts, say for $600, and then you only pay a lesser amount, say $200, by the due date. In this case, you are "carrying a balance" of $400. You DO NOT need to do this. You simply need to show usage of your card. If you continually use your card, let the statement post, and then pay the statement balance by the due date, you are not carrying a balance, you pay no interest, and your FICO benefits slightly as it shows responsible credit management.