Establish the fundamentals of the composition

I start most paintings and drawings by establishing an initial horizon line and camera position. Here, I use a pre-built perspective grid that I made almost 10 years ago in 3ds Max. Having this grid saves me about 10 minutes of hand-plotting. Sometimes I start with a rough line sketch or jump directly into a rough painting; as in this case. I don’t have a clear rule in terms of which method I prefer to start with. It usually comes down to an almost instinctive feeling before I start the piece.