the fico forums has a lot of helpful advice and tips

http://ficoforums.myfico.com/

credit karma is a site to check your credit score and to analyze your history. you can track credit here also.

my suggestion...

request a free credit report from one company, review it and dispute what's wrong, try to pay off the things you KNOW you owe, get any medical debt paid off and removed. the fico forums has templates for letters for all of this but if you request the info online, you can dispute online.

THEN in 3 or 4 months, request your credit report from another company and see how that one is and see if the errors on the first one were removed or taking care of...wash repeat.

4 months later request the third report and work on that one.

i suggest this method because you get one free per year from each company and if you stagger them you can see what's wrong with each and you can work on them bit by bit and you should see improvements by the last credit report.

HTH