I have been in the business of Sunless-spraytans for 4 years, if your clients are apt not do the proper prep for the session, they will find that the spray tan will likely come off and loose their tan unevenly, looking like snake skin. I always suggest exfoliating for several days, with shaving their legs the day before the sunless session, using a new razor and foam gel, this protect the skin from damage.
Skin types are unique, for better results there are several techniques for application
experience is the best teacher...
I would be happy to help answer any questions you might have.
Forever Young Studios
The Ultimate in Sunless Tanning
at bling in Hayden Idaho