The most important are glucosamine and condroitin sulphates. They usually come in a combination tablet. Also celery seed. And you can get glucosamine cream to rub on in some places. Ask at a health food store.

Some people like MSM and SAM-e which are also from a health food store. But my arth. doctor (at a major Canadian research hospital and university) was involved in a drug trial and DID NOT like the blood test changes in her patients taking MSM, so she stopped the trial.