Well the two things that got me in trouble were

1) Taking on more debt than I was able to handle, like cosigning for a Harley Davidson we didn't need and then my husband lost his job a few months later.

2) Don't ignore the medical bills... They do matter when it comes to you're credit.

Other then that I think everyone would agree, just make sure you pay you're bills on time and don't max out the credit cards!