Hi all,
As I only brush by hands with Humbrol paints, I use to use a neutral color as No 103 or 64. Then I sand this very thin with Tamiya's 2000 grade sanding paper.
I've recently bought Humbrol No 1 Primer but have'nt still tried it.
I also oftenly use no primer at all when the plastic has a clear neutral color such as grey as per Heller kits or Tamiya's...
Cheers,
Jicehem