Four years ago, I started to get serious about my credit scores and reports. I was about to turn 40 and had very little concept of how credit worked (apart from the obvious - you have to pay it back), or what those 3-digit scores were or what they represented. As you can see from my signature, my scores were terrible.
I made some effort to address baddies, with limited success. A couple collection agency accounts went away after a few DV letters, but for the most part I came to accept that time and a resolve to make better decisions were the only things that were going to make any real difference. I marked the date(s) on my calendar that items would drop off and looked forward to them.
I started slowly with a secured card with a $750 limit from my credit union, which I used to build a positive payment history while waiting for negative accounts to age off. Some more gardening and a few sprees, and scheduled use of the luv button, and now I have over $50,000.00 in available revolving credit (with 12% utilization) and closed on my first house on December 12. Another spree this month led to approvals for a $4,000.00 Citi Simplicity card and an $11,500 Discover it card, for the long 0% APR on purchases and balance transfers. I'm going to be in the garden for a nice long while now.
The information, advice, and support I found here were the keys. In looking back, I can't believe how far I've come.
Thank you all. We don't pay you enough. 
Starting Scores: EQ 624 2/4/13 TU 548 *ouch* 2/1/13 EX 566
Good luck in your journey!