The One Product You Need For Flawless-Looking Makeup Is…

If Your T-Zone (or Every Zone) Approaches Oil-Spill Status by Midday… Oily skin really benefits from water-repelling ingredients that draw moisture away from the skin, and a little bit of silicone to keep things smooth and even-textured. Look for mineral bases, which leave a silky matte finish without looking powdery or dry — magnesium aluminum silicate and aluminum oxides are great for this purpose. We Recommend: Hourglass Veil Mineral Primer, $52 (Sephora.com)

If Your Pores Are Huge… Skin with large, visible pores warrants the same treatment as oily skin, but you'll want to look for "blurring" ingredients, too. Dimethicone-based formulas are the most popular, because the lightweight silicones glide over pores for a smoother makeup application. We Recommend: Too Faced Primed & Poreless, $30 (TooFaced.com)

If You Could Really Stand to Lighten Up… Sad, dull skin desperately needs a good brightening primer (and let's be real, you probably also need to reassess your skin care routine); it can mean the difference between looking lackluster or looking/faking radiant beneath your makeup. Look for "optical brighteners" with (very) slight shimmer for natural-looking luminosity, and formulas that have a bit of fruit acids and antioxidants to encourage a cumulative improvement. We Recommend: NARS Light Optimizing Primer, $35 (NARSCosmetics.com)

If Your Skin Breaks Out in Hives If You Look at it Wrong… As anyone with finicky skin already knows, finding super gentle ingredients is key to keeping your complexion happy — and all too many primers contain potential irritants. Look for proven soothers like hyaluronic acid, aloe, and even a touch of oil, and avoid heavy silicones as much as possible. We Recommend: Glossier Priming Moisturizer, $25 (Glossier.com)