This season’s newest hair serums are created with subtly sunnier strands in mind. To bump any shade up a notch, celebrity hairstylist Jen Atkin advises spraying heat-activated solution, which uses a gentle blend of lemon, pineapple, and, yes, a form of hydrogen peroxide, from the mid-lengths of the hair to the tips, avoiding roots. Here, six ways to get a healthier, shinier blonde—no salon visit required.