Do you tip when you receive a facial from skin care place?

Is it normal to tip that person and how much if the facial costs 30-50 bucks?Do you tip when you receive a facial from skin care place?
i work the front desk of a spa, and it's customary to tip your service providers. it's typically like a restaurant 15-20% of your service, even for the small ones...you tip your bartender or barista for a drink right...same type of thing. these type of people live off their tips because they don't typically get paid that much :) if you tipped them next time i'm sure they'll be greatfull :)Do you tip when you receive a facial from skin care place?
you should always always always tip if the service is good.
i believe it's polite to tip, i just don't know how much