That is way to opened ended of a staement, hence I suppose why you are looking for more info. Paying everything down, depending on the situation is NOT always the answer.
But here is a site with a wealth of information. But just like anything, read, read, read.
http://www.creditboards.com/forums/
The awesome thing about credit is that time heals all wounds, but there are things you can do that can reduce, or erase that time to easily prop up your credit outlook.