Dull skin is often the result of inadequate exfoliation, so seeking a toner that helps buff away those dead cells, grime, and other buildup — aka a "glow tonic" — is important. The most common ingredients you'll find to help revitalize and brighten are AHAs such as glycolic and lactic acids. You can use these types of toners once or twice a week (sometimes daily, but do refer to the product application instructions), and then a more straightforward toner on alternating days.
