em... technique? no special technique really. pretty standard way of drawing and painting really... i do seperate my shadow and lighting layers. thats about it.
i can show u guys the steps here. step1: sketch and clean up your drawing. step2: do a flat base color first, after than do some light shadings. for this is just a simple light down from the top. then i add a grey background in another layer. put in at the bottom. step3: darken the shadow area with multiply layer, use a light grey color. step4: brighten up the light area with overlay layer *important* remember to seperate each of em in different layers. many novice like to just do everything in one layer. but u must practice and get used to seperating the layers. this will greatly ease your work when u need to change something. so thats. color, bg, lighting and shadows all in seperate layers.
yup. thats all these is to it. and if u wanna bring it to the next step. paint over the lines. for the finished look.