How many miniatures are there to paint, MaliA?
If there's a fair few I'd recommend a tin of white plastic primer spray. Will also make the colours look brighter (ideal for super hero costumes) and take fewerless coats.
Top tip, whatever paint to go for (I use Citadel stuff) always* thin it down with a drop of water (aim for milk consistency).
*unless it's a wash/glaze/contast/varnish