At first I had trouble applying the Couvre', but I'm now starting to get the hang of it. I put it on after washing my hair, add minoxidil, maybe folligen depending on my regimen. Then I put on the Couvre'.
To get a more realistic effect, I just make sure I have a little extra water on my fingers, squirt the Couvre' on, and spread it on the scalp (thinning it occasionally with more water). I start at the center of the scalp where I'm personally the thinnest. By the way, I'm a diffuse thinner too. I've got almost pure white hair (extremely thin), so the real trick for me is to thin the Couvre' out just enough to cover the shine. It's almost like mixing water color paint. In my opinion the most realistic effect is achieved by just covering the shine, not necessarily giving it a heavy coat of white.
That said the approach listed above sounds like just another way to get the same effect, otherwise it can appear too opaque. Use water to thin the makeup like texture a bit. You don't want it transperant, but just opaque enough to stop the shine. Also, don't get it "too" close to the front hairline or it will be noticable. I work from the middle outward and sort of pull it toward the front stopping when it's too close.
At least that seems to work for me.