Well... you can mix shades of color, EXAMPLE: you want to draw a sun, so you would, like, literally MIX the colors together by overlapping the yellow circle with the orange circle, but that only works in real life, in flipanim.com you would just get an orange circle, don't thank me.
Well, sketch, then you get the pen and stuff, then lineart, copy the linart, then colour, and shade, and finally, copy the line art to the coloured one.