Here's another update, I have pre-shade my Intrepid with a sharpie/permanent marker. This is a technique with I already have used with mixed results but I am giving it another try.
The seam at the back was so bad that I lost a lot of raised detail with sanding, so I just replaced the whole with a piece of plastic card.
I using enamel paints from Humbrol (because I had those in stock)
The first painting session went bad, the paint was to old and formed lumps. The second session went better. As you can see, the shadow effect is starting to come but it will take a least one more painting session.
My spray booth is not so big, making the handeling a such a large model quiete difficult.