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SIGN #1
Your hair has no volume.

The top is flat, the sides are bulky, and it no longer frames your features. "If your hair just sits there, even after you've blown it dry, set it, or curled it, at the very least get a trim," says Mark Garrison of the eponymous New York City salon.

SIGN #2
Your high school friends assure you that "you haven't changed a bit!"

Guess what? It's probably time to do just that, says Sam Brocato of the hair-care company Brocato America. Start getting inspired by collecting images of cuts you'd consider. Revisit them weekly until you can picture living with one of them. Next, schedule an appointment.

SIGN #3
Your highlights are more noticeable than your base color.

"This is an indication that your highlights have become too heavy," says Garrison. The fix? Consider a single process to cover the streaks and lay off new highlights for at least three months. (Don't worry, some of the lighter bits will naturally show through, giving you a subtler, sun-kissed effect.)

SIGN #4
You're not receiving compliments on your hair anymore.

One simple tweak sure to garner attention is to set your strands in hot rollers, suggests Federico Calce of Federico Salon in New York City. "Of all the heat-styling tools, they produce the softest, sexiest waves."

SIGN #5
Your hair and skin tone match.

If your tress and skin tones have become too close, you could benefit from lowlights, says Garrison. Add deeper, warmer streaks using peroxide and ammonia-free color to give your look loads of dimension without damaging your hair.