When I walk into St. Tropez expert Sophie Evans's faux-tanning booth , she gives me the once-over. Her eyes open with horror. After analyzing my streaking skin, she informs me that it's time to lay off the tanning. And this is coming from a woman who professionally spray tans celebrities for a living!
My problem? I had been sprayed only a week prior, and my tan was already coming off in spots where I sweat the most, like my cleavage and underarms. She explained that since I hadn't been properly exfoliating to gently remove the fading tan, adding more color on top would only enhance the zebra effect. So she helped me exfoliate, and the second tan was set. But before I left her office, I made sure to pick her brain on how to keep your spray tan going all Summer long. After all, why should those Jersey Shore kids have all the fun? Read on to learn what spray-tan detoxing is and why baby oil can be your best friend this season.
Source: Getty 
POPSUGAR: If you want to get spray tans every week or every other week, what’s the best way to go about it?
Sophie Evans: So if you want to constantly stay brown, you never want anybody to see your natural pale color. Can’t have a spray tan done once a week . . . you need to look after your skin.
Your skin will naturally shed over five to 10 days, and no self-tan will last longer than 10 days. During the summertime, it sheds quicker because you’re sweating, and you’re in and out of swimming pools and the ocean. The key is you have to exfoliate your skin every couple of days. Use very gentle body polisher and mix it with water.
PS: What areas should you focus on exfoliating?
SE: The top areas of tan buildup where it will fade first, like your neck, the crease of your arm, your underarm, and around your bra area (especially if you wear a tight bra or you sweat a lot at a gym). So exfoliate every couple of days with something gentle, and moisturize your skin with the correct product. Different moisturizing products can actually deteriorate the life of your tan.
PS: What’s a good moisturizing product to extend your tan?
SE: Something basic. Cocoa butter is lovely. The Body Shop  does an aloe vera body butter, which is fantastic. Coconut oil is actually quite nice to use on a tan . It doesn’t deplete the life of your tan, whereas if you use something with a citrus product in it, then it will strip your tan off. Use very, very basic products.
Source: NBC 
PS: What is a spray-tan detox?
SE: We recommend that you detox and heavily exfoliate your skin once a month. We want to get all the old self-tan off and to start off fresh [when you get your next tan]. It’s good for your skin, especially when it comes to hydration. Detoxing will keep your skin really nice and clean. There are many ways to do it: You can go swimming, sit in a sauna, or take a steam. Baby oil is very good for detoxing the skin if you put a little bit of lemon juice with it. Put it on your skin and let it set for about 10 minutes, then get in the shower and scrub [your skin]. The baby oil swells the skin’s surface, so when you use a scrub, it then makes the skin more pliable so that your self-tan will come off. We recommend you do this once a month.
PS: Can you use a self-tanner in between spray tans?
SE: So you definitely need one for your face. Your face will fade in about three days. I like a spray for my face. People who are prone to acne will need one specifically designed for the face because it’s noncomedogenic. When it comes to your body, you’ll want to boost the color on your legs. If you’re going out on a Saturday night and you’re wearing a short skirt, try the St. Tropez Self Tan Luxe Dry Oil  ($50) — it will look fantastic. That’s when you want to look really glam, so it will give you nice contours and super hydration. A gradual, light tan is good in between a spray tan, just to boost the color and put back what sweat, the pool, and the ocean have taken out.
PS: Is there any way to deal with sweat right after you get spray tanned?
SE: Use baby powder. It just keeps it in place. So put baby powder in your cleavage, under your arms, on your knees, behind your legs, and anywhere else that's prone to sweat.
Source: Johnson & Johnson