1. Late payments
A credit score can plumet 100 points by being late on a bill. Any bill. Getting is back up is not as easy as losing it.
2. High card balances, low FICO score
FICO or credit score ranges from a really bad score of 300 to a great score of 850. Why is this important? It's how mortage company rates you.
Also, it's recommended to only have 35% balance on your credit card. So, if you have 1000 credit limit, make sure the balance is 350 or lower.
3. Closing credit cards
Don't close the older credit card you have. It will hurt your history. You're better off closing your newest account because it doesn't have as much history as the oldies you've got.
4. Too many in-store cards
Opening mulitiple credit lines in a short amount of time can send the wrong message. Lending agencies might look at it as unstable credit risk when in fact you're only looking for a great savings of 10-20% if you open in-store credit. So slow down on those discount offered by opening a credit card.
5. Fines that add up
I think cities are catching up. Fines like parking ticket and late book fees could ruin your credit score. If they pass it to collection agency, they can really go to town on your credit score. I guess it's better to pay up or don't get fines.
On the other hand, there's seven ways you can improve your credit score.