The ideal way to use this duo is for a 60 night renew & repair. On a well cleansed skin apply either the Emergence Skin Refining Serum OR the Prebioforce Soothing Balancing Concentrate on the 1st night. The next night apply the other part of your duo. Alternate these nightly for 60 nights. After 60 days set aside your duo of treatments (keep in the fridge) and then repeat for another 60 days after the summer!