Yeah you basicaly work your way up, but the first thing you do is have a base color and then block the shapes out with the darkest shade and maybe some highlights, though that applies to painting so I'm not sure how it'd work in MSPaint
This sounds like a good way to paint

The evolution of the robot continues, heavier armor has been added to give its wearer a much better protection. The Mark III also includes higher mobility, something that the previous models lacked, and a much larger visor has been added so that the wearer will be more aware of his surroundings.
The Mark III has also an integrated powersource that not only is more efficent, but is much more protected from enemy fire since it is now part of the armor.