Cosmetic companies have been making some significant innovations with active ingredients that are increasingly exotic — gold, stem cells, radical scavengers. But they don't come cheap. Some of the best serums that I've found cost around $200 for a small bottle. So I want to give you a few tips on how to use them and, most importantly, how much to use. With the right approach, you can make these powerful little chaps last for months and get more bang for your buck. Watch my video for more.