Use a hard chair and put your spine up against it; try and keep one or both knees higher thatn your hips. A small stool is helpful here. For short rest periods, a contour chair offers excellent support.
Try to stand with your lower back flat. When you work standing up, use a footrest to help relieve swayback. Never lean forward without bending your knees. Ladies take note: shoes with moderate heels strain the back less than those with high heels. Avoid platform shoes.
Sleep on a firm mattress:put a bedboard (3/4" plywood) under a soft mattress. Do not sleep on your stomach. If you sleep on your back, put a pillow under your knees. If you sleep on your side, keep your legs bent at the knees and at the hips.
Get a hard seat for your automobile and sit close enough to the wheel while driving so that your legs are not fully extended when you work the pedals.
Make sure you lift properly. Bend your knees and use your leg muscles to lift. Avoid sudden movements. Keep the load close to your body and try not to lift anything havy higher than your waist.
Don't overwork yourself. If you can, change from one job to another before you feel fatigued. If you work at a desk all day, get up and move around whenever you get the chance.
Get regular exercise (walking, swimming, etc.) once your backache is gone. But start slowly to give your muscles a chance to warm up and loosen before attempting anything strenous.
If your back acts up, see your doctor; don't wait until your condition gets severe.