Paint and detailing tips

[Hood Gundam]

I'm currently working on an Astray Blue Frame MG model (seen here http://www.gundamplanet.com/mg-gundam-a ... evise.html) and I want to do a repaint so the blue is green and the orange is black. I'm also looking to do some battle scarring. I've had some model painting expierence with Warhammer 40K figures, but I wanted to know if theres anything special I should do to the model during painting (i.e. gloss coats) and also how should I go about the battle scarring?