As a follower of beauty expert Paula Begoun, I will summarize her advice:
Primer, then SPF, then makeup.
If you use any additional products, this is the recommended order:
1-
Toner (alcohol & irritant free)
2-
Exfoliant (such as BHA/Salicylic Acid or AHA)
3-
Treatments (for anti-aging, acne, discoloration, etc... This is where I use my Benzoyl Peroxide during the day and Retin-A at night)
4-
Antioxidant serum
5-
Makeup Primer (though a specialty treatment serum or antioxidant serum also doubles up as a primer due to the silicone content, so I personally skip foundation primers)
5.5-
Shine Stopper or Oil Absorbing Product- (Optional for oily skin) Such as
http://www.paulaschoice.com/product/shine-stopper-instant-matte-finish-with-microsponge-technology
6-
Day time - SPF - This is always the last skin care item before makeup.
Night Time - Moisturizer
7-
Makeup - Always last
Whew! It sounds like a lot more work than it really is. I used to have to label my products to remember what step they were, but now I memorize my routine.