In assembling the Storm Eagle, I found that I needed to paint some of the interior before I continued. Hence I applied a black base coat and roughly painted some silver on most parts. I'm yet to finish this process, but its getting there. I don't think I need to be particularly complete or careful as the interior of the fuselage is not going to be seeing the light of day too much in all regards.
Getting the engines on the sides of the flier was a bit tricky. I strongly advise that others who are following this series dry fit several times to get it right (measure twice and cut once and all that jazz). The really hard bit was attaching the side of the fuselage to the floor though. Even though I had spend some serious time getting the sections straight with liberal use of hot water, it became clear that I couldn't get it perfect in the finite time I have for the hobby. Hence, I firmly pressed the two segments together and drilled through at a 45 degree angle to each piece to apply a subtle paperclip size pin to keep them together along their length (about four or five in total). Together with trusty superglue, this is more than enough to keep the segments behaving themselves and in place. I will probably go back later and greenstuff over the holes prior to painting the exterior.
The next few steps will be attaching the second side of the fuselage and then working on the cockpit. Again with the cockpit, I anticipate that I will paint the interior before placing the space marine pilot in to place. But this time, its more important to get the painting right as most assuredly the computers (etc.) in the cockpit will be seen by the exterior world.