What are some ways to prevent arthritis when I get older?

Avoid overweight. Staying close to ideal body weight is the only way we can prevent degenerative arthritis. Foot arthritis could probably be prevented by avoiding shoes with a tapered front. Special cases include preventing gout by staying thin and avoiding too much red meat, fructose, and alcohol; and preventing lyme arthritis by wearing deet and doing tick checks daily in summer in endemic areas.
Arthritis prevention. In reality, arthritis is simple age related wear and tear which cannot be prevented. This is largely genetic. However, maintaining proper weight and nutrition, as well as low impact exercise may be helpful. Avoiding injury can help prevent premature joint damage leading to arthritis. Also, some limited success with glucosamine and chondroiten sulfate to slow progression but not cure arthritis.