You learn to see complex spaceships as simple geometric shapes.
The "Sketching from the Imagination" series by 3dtotal Publishing has become a staple for concept artists. The Sci-Fi edition, specifically, gathers the sketches and insights of 50 professional artists. It focuses on the raw, unpolished phase of creation where ideas are born. Why Concept Artists Seek This Resource
Find on specific sci-fi sketching techniques (like mechanical joints).
The book covers everything from "cyberpunk" and "space opera" to "biopunk" and "retro-futurism." Core Pillars of Sci-Fi Sketching
High-contrast renderings that show how a doodle becomes a masterpiece.