You can see in these images  of her work that she uses very heavy, opaque colours and thick brush strokes to achieve the look of a 2D painting. I think its her pespective, angle, colour choices and placement which make her work so effective. As she doesn't want to make her models look realistic, she has to visualize where the shadows and highlights would be, from whatever angle the model will be posing from. I think the boldness of the lines help create the 2D effect, as it remove all the tiny details of real skin, as well as the translucency. I can see how important getting the right colour tone is . In the painting of the girl (below) there are a lot of colours going on but they make sense cohesively, which is helped by the direction they are painted in.