Vic, first, apply the decals to a gloss surface, preferably using a decal solution, such as Micro Sol and / or Set. If there are signs of 'silvering' when set, then prick the decal with a pin, and apply more solution with a brush. If there are still edges showing, they may need painting-in. Sometimes, some decals never seem to be free of all silvering, fortunately fairly rare these days. On the Corsair above, I think perhaps the decals were applied direct to a matt-painted surface.