Update 1
After looking at more angles of bootys along with my original sketch, I posed my reference model, and turned it slightly from the concept, since I realized I could get two boobs in there! From this point I shall continue to refine proportions. and shapes
Update 2-( Main Image)
I find that with my 3D ref, the perspective never hits that extra oompf fully, So I use it as a beginning guide of character proportion, then I will expand tweak. So for this, I enlarged the buttocks, and shrunk the head slightly to add some more depth!
With perspective shots that I render, I like to hold back on my thicker line variations, until the tail end of the piece. Next I will proceed to color and light