Apply two or three drops before moisturizer, either all over or only through oily, redness-prone areas. Five percent niacinamide is a sensible middle ground for excess oil, the look of pores, redness, and uneven texture without starting at the internet-favorite 10% or 20% end of the pool.
Begin once daily. If your skin is already happy, this is optional rather than a tax for being in your 20s.