Go to www.egoscue.com and browse through the sight.
Buy his book Health through Motion for $10:
This can all be cured through simple stretching and strengthening exercises, but it is difficult to do without first understanding how everything is connected. For example, I have hamstring problems that I often solve by stretching my hip flexors, abs, and theighs. “What? But aren’t they on the opposite side of the body?” Yes. But when they get tight, they rotate the pelvis forward causing a stress in the hamstring.
You can do a self diagnosis in the book and start doing the exercises and see some progress. For about $40 (I think), you can send them pictures of yourself and get more specific exercises. For $250 you get a personal appointment. My posture has improved imensly in the last 4 years by doing exactly this.