Primer / Undercoat prepares the surface for the basecoat. Something to do with "adhesion" - But the opportunity is there to spend more time preparing for the basecoat. You want a smooth surface. A "flat" smooth rather than a "finish" smooth. Then the base should go on like glass - but that's only for the decal to be applied to a flat surface. A clear is overkill. Even the clear will have the extra step of scuffing the surface to allow the decal to adhere to it. A light scuff is a good idea on the basecoat. I never clear cabinets.
