Acrylic paints really like two things: an established basecoat on whatever they're going onto, and to be thinned out a bit (a drop of water for ever few drops of paint, say). High density pigment ones take thinning better, but even those grainy cheap ones spread better when thinned - a drop of an acrylic matte/gloss can make them seem more vibrant and smoother than they are, too. That's what I learned with trial and error when painting sculptures I'd made, at least.