Home Exercises and Stretching
A highly recommended book to start with is Robin McKenzie's "7 Steps to a Pain-Free Life: How to Rapidly Relieve Back and Neck Pain". These exercises don't help everybody, but for a sizable portion of the population they do a great deal of good.
Also, consult Pete Egoscue's "Pain Free: A Revolutionary Method for Stopping Chronic Pain". You can also receive expert advice from Postural Restoration Therapists and Posture Alignment Specialists (PAS). See egoscueuniversity.com and posturalrestoration.com
Other Behavior Modifications
Many people with lower back pain find that bad posture while sitting contributes to their pain. A good chair can help alleviate this problem, but a cheaper and more universal solution is a lumbar support roll. These come in many forms, from the home-made to professionally designed solutions sold in most back-pain stores.
A lumbar roll is placed just above the belt line, while sitting up straight in a normal chair. It causes your spine to bend forward in the same way it should naturally, but is often lost with age.
Two easy home alternatives to a lumbar roll is a roll of paper towels (Small sizes work best) or a rolled up towel.