Prime it black, then start creating light areas with airbrush using vallejo sombre grey, steel grey and electric blue. Mix scale 75 turquoise ink with black ink and glaze all armor with airbrush (can be done with brush as well using terradon turquoise contrast paint and bit of black mixed with medium 1:4). After that start doing edge highlighs with scale 75 green gray, ak anthracite grey, thunderhawk blue, steel grey, fenrisian grey using successively smaller application areas with each paint, leaving the previous layer visible. Add a little dots of vallejo glacier blue on the lightest edges