Here is the mech, based and ready to prime. I added a little scrap to the base, since there was a lot of open space when mounted. I filled the base with vinyl spackle and sand to build it up. I worked it up the feet a little, to give the impression of the mech sinking in the mud.
Here, I have primed the mech with a brown Krylon primer, to give me a rusty base to start off with.
My next step was to drybrush the entire mech with white, so that when I go to lay down the next layer it has some brighter areas.
Next, I did a heavy drybrush of Steel. (I think this is an old Armory color that I have had around for years. Gotta love those old 4 oz. bottles.)