First of all, leave purple shampoo for blondes, grey, and silver-haired folks—the color deposits won’t provide the same protection from color fade or brassiness or brunettes or other colors. (Alternatively, many brunettes have now turned to blue shampoo for a similar effect.)
So as long as you fit the blonde or silver bill, you can use a purple shampoo: but sparingly. First, completely soak hair through in the shower, and if your hair errs on the drier side, consider conditioning hair first. By concentrating a hydrating product through the ends and rinsing, you’ll be able to achieve more equal pigment deposits when washing with a purple shampoo.
Then, rake a dime-sized amount of purple shampoo and evenly massage through scalp strands. If you’d like to start slow, try mixing your purple shampoo with your favorite formula (ideally something tuned to your hair type or texture). That way, you can reap the color-depositing benefits of a pigment-enriched formula while also treating your strands to a customized cocktail of whatever it needs. For me, I’d probably use a frizz-reducing formula to combat my postpartum baby hairs and cowlicks, but you could also try a damage-repairing formula, a volumizing one, or even just something that has an incredible scent. (All. About. That. Fragrance.)