Hi Airmech,
I also use the hairy stick to slap the paint around and I am a keen user of Klear.
I would suggest that the Klear is laid down over the whole model as will prevent tonal differences and possible different coating thicknesses causing "steps" in the final finish.
A couple of thin coats should suffice to produce a smooth surface but allow each coat to dry.
You can also use Klear as a setting solution for your decals. To help things settle down put a dab in the area your about to place the decal.
With the decal in place, do the usual and sop up the excess fluid. As the decal starts to dry I have a tendency to brush on another thin layer of Klear to help the decal snuggle onto the surface. Once cured, Klear produces a good hard surface to protect the the previous layers and can be evened up with a polishing pad.
I have found that for the final sheen, that the Humbrol Acrylic Rattle cans are pretty consistant in producing the desired effect. For me, this is undertaken in the garden on dry windless days, which means I don't finish many models except in batches!
HTH
Darren