To shower or not to shower after tanning that is the question to be discussed here. Much will depend on how you are tanning, whether cream, spray or tanning bed.
Tanning method and shower recommendations
Tanning bed. It's best to not shower for at least four hours after exiting the bed. Your skin is still in the process of tanning even after you've left the salon and showering will stop you from getting the full results of your tan. If you want to shower before you tan, do this a couple of hours ahead of time. This will allow your skin time to dry and absorb the moisturizing cream you'll layer on afterward as you do want to moisturize your skin regularly, especially right after you tan. This will enhance your tan.
Sunless tanning lotion. Be sure to shower a couple of hours ahead of time and do not moisturize. The lotion will need to stick to your skin and it won't do a very good job if you have moisturized within hours of trying to apply the sunless cream. Apply sunless cream in circular motions to try to evenly distribute the cream so that you won't end up with streaks. Get a friend to help you apply the lotion to your back.
Spray-on mist tan. Shower a couple of hours ahead of when you plan on spraying the tan on. Don't shower for at least four hours afterward so that the lotion can set properly. When you do shower, just use a mild body wash or soap and don't rub at your skin with sponges, cloths or anything else. It will remove tiny layers of skin cells, which will shorten the length of the tan look.
Before you tan, exfoliate your skin a week before and then a day or two before you tan for the first time. Tanning dead skin cells that will slough off won't give you the effect you are looking for. Exfoliate before and don't exfoliate after any tanning process as it will just be removing the tanned skin cells. It you are tanning using a tanning bed, be aware that you may not tan on your pressure points. Your skin is under pressure when you lay down as well as with any grevaces like finger folds on your knuckles. Be sure to shift your body around while laying to change the areas that are pressed up against the bed and flex/wiggle your fingers so that the rays get to all areas evenly.
With sunless tanning lotion, always wash the cream off the palms of your hands really well. Otherwise they will turn orange.