Hi,

I did paint the parts like it would have been on a real tank : all the tools, fittings, detail parts were painted before assembling, the tank body itself was painted like you can see on the photos of the first page of this thread. I made the wash technic.
After I assembled the parts on the painted tank (I used CA glue, after I put a drop of CA glue from the inside when I had a "hole and pin" configuration)
Then only after, I began rest of the weathering.

Anyway, try your own technic, with the way you want, just have in mind that it is not possible to do a good job with the painting if you assemble completely the model and after you paint it, it is not possible to be precise and accurate.