Shower, exfoliate, and shave the day before your tan, or at least 8 hours prior. Avoid scented lotions or oils that could stick to your skin.
Wear dark, loose clothes that can get stained.
A typical spray tan will last 7-10 days, but this could be affected slightly by your skin type, and how well you follow the post tan instruction care card given at your appointment.
Between 2-8 hours, or even the next morning depending on the type of tanning solution chosen, and desired level of darkness.