A good rule of thumb in the proper use of skin care is to go from the thinnest or most liquid texture to the thickest, with the most potent 'active' products first, and sunscreen always last.
Let’s say you have chosen a facial cleanser, an antioxidant serum, a moisturizer and sunscreen to use in the morning. Cleansing always comes first. After that, you want the powerful ingredients directly on your clean skin. So the proper order would be
3. Moisturizer (lotion, cream or oil)
What if you like to use a toner, either for the pleasant scent or to remove any traces of cleanser or makeup? Use it after your cleanser, and before the serum.
In the evening, follow the same thin-to-thick rule: cleanse, apply serum, apply treatment lotion or cream and/or moisturizer last.
(TIP) If you apply moisturizer before the serum, it will weaken the effect of your power ingredients. If your moisturizer is a treatment formula that contains actives, simply follow the thickness rule, and apply it after.
Be careful not to irritate your skin by applying multiple ‘active’ products on top of one another.