Sketch up. Quarter view
Create Selection and Mask it. This makes you work faster. You can fix the shape in the mask. You will never worry about drawing out of the out line once you finish this process.
Tip: I like to mask this base shape on a group which includes all the value, detail, color and adjustment layer in it.
Organic Design step1
Pick the 3/4 front and Organic Design Step2
Value & Shading
80% done. I will do the rest detail in Zbrush directly
Sketch out the anatomy reference for the base mesh.