I was messing around with techniques for painting power armour and I think I've stumbled upon a winner which looks pretty good and takes little time/effort. It's not an unknown technique just one I haven't used before.
First you base the mini in whatever black you use normally. Then apply a complete drybrush of grey, and on top of that a drybrush of white. What you want is a version of your finished mini if it was in greyscale instead of colour. Then using the tamiya clear range of paints I apply colour over the top, and paint anything that would be metallic. Finally the whole thing gets a brown wash, is varnished and based. Here's the result on a space marine I had lying around: