What's the best way to stretch my tight back muscles?

Bending: Stretching exercises that bend, extend and twist at the waist are good starters. Don't bounce when you stretch though. Stretch as far as you can, then hold that position for a count of thirty seconds, then try stretching farther two more times in the same directions. Don't just stretch in one direction, but try to stretch you back in all directions. You can find some good stretches on the net.