The link below is from the Consumerist about using credit cards wisely. There's some good advice here.

Here's a quick summary:

1. Pay off your balance each month
2. Get a rewards card and maximize use
3. Check your credit report (Fico Scores/Reports)
4. Pay all bills on time (Automate your finances)
5. Avoid ID theft
6. Take advantage of no interest, no payments deals, but pay off on time
7. Avoid paying interest on consumer debt
8. Don't max out your cards
9. Don't close credit card accounts
10. Don't obsess over your credit score

Be Good: Consumerist's 10 Commandments of Credit – Consumerist