We've been preaching the gospel of retinols for ages — and we're not alone. Talk to any dermatologist and they'll likely agree that there's no better ingredient to help you get the skin you want. But there are still a few common misconceptions: namely, that retinol is only useful at a certain age to nix wrinkles and such.As someone in her 20s who has seen retinol help clear up her acne immensely, I consider it my charge to spread the gospel of retinol. So, I picked the brain of skin guru Sunday Riley — yes, the woman behind the eponymous line — about the ins and outs of skin care's star ingredient."Many people fear that retinol will make their skin red, flaky, and irritated, as that is a common side effect from most retinol-based products," she says. "However, with a high-quality, well-formulated product, it can be an effective tool in the battle against acne, pore size, and wrinkles, with little-to-no side effects."Ahead, find Riley's guide to retinols, as well as some of our favorite picks. You'll be welcoming this super ingredient into your skin care routine in no time — probably with open arms.