What are some commonly-used methods of relieving constipation?

Stool softeners. I usually recommend a high fiber diet such as prune juice and/or stool softeners such as colace twice daily and/or MiraLAX (polyethylene glycol) daily work well.
Laxatives. Fruit juices, prunes, increasing water in diet, MiraLAX (polyethylene glycol) (which is not a laxative and therefore has fewer side effects).