I draw a basic perspective grid. I keep it loose – it’s to guide the design, not shackle it. The point is to inspire. I then use the Marker tool and select a grey tone a shade darker than the background. I lay out the basic shapes of the craft here, using broad shapes. I don’t worry about details – just focus on proportion, perspective and an interesting angle.
I use a darker grey marker and solidify the primary shapes of the vehicle. In addition, I layer in tone to further define the mass and light direction. Just like working with real media, I start light and then add darker tones.