I’m a beauty therapist and give massages and spray tans all the time… if you have had a spray tan before you will/ should already know this to start off exfoliate the day beforehand, at this time shave/wax and moisturise the skin. on the day don't wear any deodorant, or moisturiser or make up (come in to the salon as a fresh slate) as this will ruin your tan and of course have a shower. you can go bra-less = this will give you a better looking tan. also the underwear should be old ones that you don't mind getting ruined; they should also be revealing (i don't mean you have to wear a g-string/thong but something that will cover you but at the same time wont cover too much to make the tan look funny)
always listen to the beauty therapist's instructions on turning, body placement and when to hold your breath (when spraying face)
also where flip flop (havaianas) shoes and very baggy (old is best) clothing (as it takes a few minutes for the tan to dry). don't shower for at least 8 hours after the spray tanning.
After the 8 hours you can then have a shower and you can then have the massage. The oil that is applied when you have the massage will help to make the tan last longer also every day after apply moisturiser or massage oil yourself. By applying the oil/moisturiser you will have a really fresh look when you go on holidays. Hope this helps and have a great time away on holidays ;-)