One tip I will give you is take the time to rub in moisturiser preferably the same make as your tan onto hands, little bit on elbows, knees, ankles and bottom of feet to make sure tan does not go into dry blobs of brown. I moisturise the inside of the hands at the end of the tanning and wipe of with tissue so the hands are not stained in any way, make customer aware no tan on them, if they go brown later it is because they are messing with themselves!! Do the whole tan first, then use a towelling mitten to lightly dab drips etc, it also gives you chance to see it you have missed anywhere. Some spray machines have somewhere you can tighten the nozzle, so less spray is coming out. It is trail and error and practice, practice practice! Stay away from feet and hands only do light spray. What are you using for screens, cos I have just designed and had a portable cubicle made, available from the beg August. I was fed up of looking unprofessional and worrying about overspray in peoples homes!! Great for salons too. Take a look on website
www.spraytancubicle.com !! It is so quick!