I generally start by making a series of simple compositional sketches. I'm looking for a pattern that's both dynamic and interesting. I do several on a page so I can compare them and not fall in love with one idea too quickly or keep repeating the same idea (Fig.01).
Next I work out a quick color sketch. The values assure me it's a good composition and now I need to establish some mood and light. This isn't done with a lot of detail. It's more to develop the look in my own mind so when it comes time for the finish I have a clear idea of what it is I'm trying to achieve. You'd be surprised how important that is. For something this finished I want my own clear goal and not to wander around hoping to "find" it. That's what the sketches are for (Fig.02)!
I block out the entire image in big simple tones and shapes before getting into any detail. This is very important and I do it for two reasons. The first is so I can keep the details within their correct value range and secondly I want all the big geometric shapes established first with their correct color/value. If every highlight and every shadow in every area is pure black or pure white the image will have no sense of believable space. It will look like a checker board instead of the simple value plan I established in the first sketch. If you get this part right the painting has a complete look to it right away. This is extremely important and I'll spend some time adjusting colors and values until it looks "real" to me. I'm also looking for simple separation of the planes. Meaning: light side, shadow side and roof tops for the buildings (Fig.03).
I next start working on the details of the small village. Since this is one of the main areas of interest it'll be important to get it working right away. I redo the first roof tops a few times until I find the right level of detail. I'm also looking to establish scale which, if I follow it, will lend consistency and believability to the piece. This is another very important and often overlooked part of the painting process (Fig.04).
Now I'm working on the rest of the town, keeping a careful eye on scale. If the windows and doors of the buildings in the back are, say, three times as big as the front, my illusion of perspective will be destroyed. I'm working my way towards the ship, adding ideas like chimneys (Fig.05) and I'm also starting to make some finer detailed parts near the bottom of the ship and the bridge structure leading to it. I do these on their own layerand completely flat so that I can judge silhouette and shape alone. If the shape isn't interesting I'll work on it until it is. It's so much easier to judge this without any modeling or detail to distract from the abstract shape (Fig.06).