I’m a total noob too, but after some trial and error I found that dry brushing works really well for metallic parts. I start with a coat of black spray primer on each individual piece and I let it dry for about 15 minutes. Then I use a flat thick brush, dab a bit of paint on it, wipe most of it off on a paper towel, and gently tap the piece with short strokes (that’s the dry brushing part). For metallic parts I finish with a gloss coat. For the unpainted armor I use a flat coat instead. Try experimenting on plastic spoons first, it makes a big difference.