It was messy drawing to life up the forum little bit so there is not much to show in it.
First, perspective and proportions are off, shadows are messy and details are neglected.
Actual effort was put in the front dwarf (still bit shabby) , where colours and shades are most important in sculpturing the deepth. It is also good idea to not only change the shade/tint of colour, but colour itself when adding lights and shades to object.
I'm sorry I can't tell more, as this isn't the finiest piece and answering specific question is much easier ^^'. But thank you for your comment : )