How to communicate skincare routines to customers with sensitive skin at a beauty salon

After working in skincare and spas for a long time, you can't just take a sensitive-skinned customer's word for what they can handle. I used to have customers say they were fine, only to have their faces turn red for two days after the treatment, which made explaining the situation very difficult. Now, I first ask about any recent acid peels, medical aesthetic procedures, ointments, and allergy…