Ddl, if you start with white base/primer , you can then paint over with any colour to achieve the shade you want. If you start with darker base/primer , you have limited your shade options severely ,straight away. You can achieve any shade/colour over white , but not grey. You can use transparents layered on white to achieve bright colours, and add transparent black for darker shade. If you use grey primer with transparents your colours will be very dark. You can use opaque colours on grey but why handicap yourself ? Regardless of whether your using opaques or transparents, you can't go wrong with bright white base. Metallics tend to look better over opaque black, but again you can paint a black back on a white lure then spray metallic over that part if for instance you wanted a silver back on lure........glider