Tom, I explained the smoke in the A/C thread, but cause I like ya *cough*, I'll give ya some more info here.
What I do is mix up around 30% smoke, to a custom thinner mix, made up of distilled water, alcohol and acrylic retarder.
The smoke is hard to see to start with, unless you lay it on thick, which looks 'fake' IMO.
With the thinner mix, it takes around 3 coats to stand out to the casual observer, but during those 3 coats, it can give just the right amount texture to an otherwise dull panel line.
The demarcation lines on the wings are quite sharp after I sprayed them using the Blu Tak method, but 2 coats of the smoke, and it softens them up nicely, wthout creating a stark contrast between the colours.
This is the same with the entire kit.
Usually msot people will pre or post shade, but the smoke seems to nail it after a little practice.
The custom flat coat makes a HUGE differance also, cause there is almost zero reflection, and just a touch of sheen.