You're on the right track Pete.
If the coat of Klear has left the model nice & glossy, apply the
decals. The gloss coat will help to avoid silvering.
Once the
decals are dry, add some more Klear over them. You can either go over the whole plane again, or just over the
decals themselves.
Once the Klear is cured, add your wash. People often think of washes as part of the weathering process, but I don't. To me, it's a vital step to give the model depth & so avoid that 'toy-like' look.