So not 100% pre shading since the tank is already painted but you get the drift of the technique. It basicly how to layer your paints to have a darker effect in some pre determin areas!
Also I would like you guy to check out http://www.thepainteddragon.co.uk/shop/ if you have time. The guys over there gladly decided to sponsor and suport Ichiban Painting so if you can show them so love ichiban style!
Cheers
Hugo