There is a series of recommended exercises to help maintain some mobility within the joints. I have provided a link to some recommendations from the Mayo Clinic, in the US as an example.
http://www.mayoclinic.com/health/arthritis/AR00030
Sorry to say that the evidence of any significant clinical benefit from "joint supplements" is poor and sparse. Quite a few anecdotal narratives from people who feel they have benefited from taking glucosamine, so it might be worth giving it a go - but do not be too over optimistic about the benefits :)
Link below to a large, well recognised recent study in the US looking at therapies for osteoarthritis. Neither glucosamine nor glucosamine and chondroitin combinations showed evidence of offering any clinically significant benefit.
http://nccam.nih.gov/research/results/gait/qa.htm