Hi James,
Over many years I believe I've tried nearly every version of "clear" finish on the menu. Lately I've been using Tamiya products and I am very pleased with the results. I like a Semi Gloss/Satin overcoat on most WW.I subjects for which I use:
A mix of 7 parts Clear Semi Gloss X35 to 3 parts of their Flat Clear XF 86. I then thin that with 40% of their X20A Thinner for airbrushing or hand brushing on smaller parts. I'd suggest you experiment with the ratios of the flat/semi gloss to get the finish you desire. I don't use lacquer thinner (as I do with their paints) because I worry about damaging the decals with the final over spray coat. So the method is primer if required, color coat(s), several coats of Future (or their gloss clear) to provide a shiny surface for the decals, then the "satin" over coat.
I'm quite pleased with the stuff; it's easily available, reasonably priced, dries quickly, and works well.
Hope this helps.
Cheers,
Lance
Cheers,
Lance