'I moved to New York when I was 18 to study fashion design at Parsons. I worked in the fashion industry after I graduated, but I realized fine art was my 'true calling.' So I transitioned into fine art by doing self-portraits on nights and weekends in 2007 and 2008, just as a side project. I didn’t show them to anybody until 2009, and I exhibited my work for the first time in 2010. It’s been an interesting transition but I love making art so much. It is my life's true passion.

I’m a mostly self-taught artist. I studied design, and within design school they do teach you some fine art, but I’ve never taken a photography or painting class. But fashion illustration led me to doing self-portraits, organically. I didn’t love the way the classic fashion figure looked in my illustrations at Parsons—it didn’t excite me—so I started taking pictures of myself to give my fashion drawings a more realistic size and dimension.

In the past, I’ve done self-portrait series of alter egos that are symbolic of various parts of my personality and character traits. Gia Condo exemplifies the more aggressive, wild, punk side of my personality, whereas Rosemary Myst is an example of the more passive, romantic side. Gia Condo is based on the Mona Lisa and is liberated, free, crazy, and experimental... Rosemary Myst is my favorite alter ego of all time. She’s based on St. Teresa of Ávila but she’s really, in a way, like an early Tom Ford character, and very fashion-y. Her styling is very ‘70s, overall, with her fair skin and curly red wig. My latest project, though, is a series of 24 self-portraits that have no alter egos. They’re just me. I thought it was time to shed a skin and do a real, genuine self-portrait connecting with the viewer.

I wear so much makeup in my self-portraits that, in real life, I prefer not to have a lot on. In the summer, I just use Diorskin Nude BB Cream to even out some of the spots, a light coat of DiorShow Iconic Mascara—it’s the best because it doesn’t clump—and lip gloss. I like Dior Addict Lip Gloss in Diablotine, or just Osea Eyes & Lips cream, because even when I go out, I try to keep my makeup low-maintenance. Sometimes I’ll do a darker lip in a berry— Diorific—or a red— MAC Ruby Woo—but lately I’m more into the berry. To give my lips a bit more pigment in my portraits, I fill them in with the Nars Dolce Vita Velvet Matte Lip Pencil and then put lip gloss over it.

I do a lot of self-portraiture late at night to have better control over the lighting, which means I spend a lot of nights without sleeping, wearing heavy theater makeup under hot lights. It all does a lot of damage to my skin, so it’s really important for me to keep up with my skincare routine. I am obsessed and addicted to devoting my life to Ling Skincare. I started using her products when I was 19—I had so much acne and my Parsons dorm was across the street from her spa—and now I’m 30 and I do not have a wrinkle yet. It changed my life. I go to her for facials, and I use all of her products. I exfoliate every morning, or, if I need it, twice a day, mixing a quarter-size of Ling’s Purifying Facial Cleanser with the Triple Action Exfoliator. Then I use the Replenishing Hydrator morning and night—I swear by that—with Squalane Hydra Boost. Moisturizing is the key to good skin. Two or three times a week, I’ll do Ling’s Ginseng Therapy Moisture Mask, which is God’s gift to hydration, and in the winter, I add in a serum like Oxygen Plasma Potion to keep my skin really moist.

I have a little trick that Ling taught me for applying makeup versus applying moisturizer: if you think of the pores of your face like they’re shingles on a roof, when you’re applying moisturizer, you should move upward, to get the moisture up into the pores, but if you’re applying makeup, you should apply it with downward movements, so you don’t clog your pores. When I do get blemishes, aloe vera plants have been a lifesaver for me. I just cut a piece open and stick it on the blemish.

For the rest of my skin, I swear by Epsom salt baths twice a week. They make my skin flawless. I put a pound of Epsom salt in lukewarm water—not hot—to detoxify my body. I read about Stephanie Seymour doing Epsom salt baths when I was 16, and I’ve been doing them ever since. [Laughs] I moisturize with virgin coconut oil, and for fragrance, I like to mix three perfumes— Nightscape by Ulrich Lang, Balenciaga, and Tom Ford’s Black Orchid.

I also put the coconut oil on the ends of my hair when it’s feeling dry. Otherwise, for my hair, I like Whole Foods 365 Lavender conditioner, which is sulfate- and paraben-free. But one of the best beauty products of all time is apple cider vinegar. If you put it in a spray bottle, with equal parts vinegar and filtered water, and spray it on your head every day after you shower, your scalp will have a perfect pH balance. I massage it in and just dry my hair normally.

I’m a health fanatic—I really believe in it. I’m very aware of what I eat, and I take a lot of vitamins. Flora Premium Herbal Formulas Vegetal Silica Vitamins have made my nails very strong, and made my eyebrows grow back after the Gia Condo series like a charm. For my skin, I swear by watermelon—it has become so much more moisturized because of it. Cucumbers and celery are great for the skin, too, because of the silica. In general, I don’t eat any sugar—only fruits—I don’t eat dairy, and I don’t eat a lot of gluten—mostly just brown rice. I was a vegetarian, but I need animal protein; I can just feel that my body is better with it. So I eat organic eggs and wild salmon, and once every two weeks I’ll have a really great organic piece of red meat. For breakfast, I have hard-boiled eggs, watermelon, banana, and blueberries with a glass of grapefruit juice. Then for lunch, I’ll have a salad of cucumbers, celery, salmon, and kale. For dinner I might just have steamed vegetables with olive oil. My favorites are yams, squash, broccoli, and kale. That's pretty much been my diet, give or take some organic red meat, since I was a kid. It’s pretty easy to maintain, even when I travel, because vegetables and fruit are usually easy to come by. My biggest vice is that I drink a lot of caffeine by way of green tea and coffee.”

—as told to ITG

Andrea Mary Marshall's latest exhibit, Sacred/Iconic, opens tonight at Garis & Hahn Gallery at 263 Bowery in New York. On view through October 19.

Andrea Mary Marshall photographed by Frances Denny on July 25, 2013. See Frances' other work here.