I always start the drawing and the painting with the face. It seems I need to get that down first before the rest can follow.
I like emphasizing shadows on the floor to really ground the figure. Without them, the person can look like they're 'floating'.
12x16" - original watercolour painting
Here's the finished product. I did his portrait first (last post) then, realizing how cute his t-shirt was and how interesting his seated body language was, I decided to do this much looser full figure.And finally, here is a close up of it.