I think the main worry here is the fine details. Too many coats can serve to muddy things up, or so I hear. The Krylon paints I use are paint plus primer so they tend to coat really well. I think the best way to handle it is from light colors to dark colors to get the paint right with the fewest number of coats.
Tom, in your original post, it looks like to me that you are sitting in cab# 73 of the White Pass & Yukon' Mikado Type" steam engine (oil tender of course).
Two days ago I just took delivery of the LGB/Aster (brass) White Pass & Yukon, Cab#73 in G scale. It's a beauty with full sound and smoke. My photography skills aren't the greatest and I think there is a post on this forum on taking and posting pictures so I should give it a try.