Warm blonde hair — even shades that are “au natural” — can look like a bad dye job when paired with cool neutrals like taupe. Notice how Lively’s hair looks more ratty than shiny? It’s not her blow dryer’s fault.

“Taupe is horrible on a warm blonde because it makes her hair look kind of green,” Kirsh says. Remember summers when you spent too much time in the pool? Not a good look. Other neutrals to avoid: Virginal white and silvery shades like pewter and heather gray.