Need some schooling on vitamins and supplements please?

Was considering taking a fish oil, glucosamine, or something for joint aches. Don’t really believe I have pain yet. As a side, may also do an over the counter Testosterone supplement. Realize this would need to be balanced with an estrogen blocker or balancer according to research. Don’t want to throw my system way out of whack with too much, so I would want to do a very low dosage. Guess I’m realizing age is starting on me and though excercise and a healthier diet has helped, just wanting extra motivation. Would say the aching is the more important part of my question though. Any experiences or help? Thanks for the replies!