How To Avoid Effing Up Your Expensive Spa Day

A relaxing day at the spa isn't cheap. Whether you're posting up at a swank hotel's steam room before a much-deserved massage or spending your Saturday getting your detox on with a laundry list of treatments, chances are you're splurging, with both time and money. Therefore, precautions must be taken: Don't eff up your spa day!

It may sound dramatic, but eating the wrong foods, wearing the wrong undergarments, and using the wrong skin-care products the day before your treatment can all turn your blissful retreat into a source of stress.

To help you get the most out of your day, we've compiled 13 common mistakes to avoid. For advice, we tapped Regine Berthelot, lead aesthetician for Caudalie Spas, the brick-and-mortar incarnation of the French skin-care brand; Courtney Palmer, general manager of Thibiant Beverly Hills, one of Los Angeles' finest spas; and Laura Benge, national spa director of Exhale, a rapidly growing U.S. chain of spa-fitness studios. Take it from the pros — no tip required.