Before you put the decals on spray the model with future floor polish or an equivalent glosscoat. when it dries then put the decals on. On top of that you can put on solvaset to make the decals snuggle down over the bumps and settle in the cracks. When all the decals are dried on then spray the models with a dullcoat. and thats it!
good luck, and I hope to see it soon.