If you have the Vallejo newish metal color in the larger bottle with a flip-open cap, it is a good acrylic metal paint. There are actually several shades of aluminum (and chrome, burnt metal, and gunmetal), so you can vary the color for some panels to make a good contrast.
I would prime with a true primer, like Badger's Stynylrez metal color or black, but maybe what you have already done is enough primer. I would not spray directly on bare plastic, and these metal paints bubble/foam a lot if you shake them too hard - I add stainless steel ball bearings to help the mixing. They take some practice for good brush painting. HTH.
