[Andrés]

Best angle will depend on the shape of your ship, most shipset use somethim more or less isometric, but some ships look better from al almost frontal angle.

Background must be pure black and no shadows in the ship must be pure black so they don't look like holes. To mask correctly in 65k colors darkest shadow need to be something like RGB10,10,10.

I don't think there's any other problem with colours.
A good set of lights, especially if casting shadows can really improve the look and make minis less flat.