If your doctor agrees that you need supplements, remember to take them. They can do nothing if left in the bottle. Set up a daily routine for taking them and follow it. Remember too if what the salesperson or the packaging advertising says is something that is too good to be true, it probably is. You should avoid those making unrealistic claims. Expect only what it would do for you if you were eating sufficient quantities in your food, not what people want you to believe to make a sale.
Take time to read the WebMD article carefully as it has some pointers not included above.