two things that hurt your credit bad. Divorce and buying a home.
When I started Sprint, my credit was real bad. I lived in an area where there were more people then jobs. All factory work too. No training or skill needed. The companies would hire you then lay you off before giving you benefits. That meant no medical insurance. I got sick, had my appendix removed, and a few other health related things with the wife and kids. No insurance. Except when I had my Son. We planned him the responsible way. My wife had insurance during that time. Anyhow, it cost you about $200 to sign your name at an ER. $400 an hour for a room (that did not include a hooker), $7. 50 per aspirin. Etc. Try paying that making minimum wage or unemployment.
I ended up moving 1500 miles away to get a good paying full time job. And it HURT my credit. The credit companies then said I was trying to run away from my debts.
It is hard as hell to build credit, but easy as sin to destroy it.