Its always worth playing around in Photoshop, just to keep the hand in with getting the techniques right. This was just an exercise in practice originating from a hard black pencil sketch... turned out ok! :)
Full rendering, built up as a series of layers and compiled for one scene..
Linework is important, especially with weighting. Heavier lines should always be applied where there is 'air' behind them. This makes them stand out and gives the impression (or illuson) of physical depth and distance between objects.
Brief composition of the process involved in pulling the work together...