Clarify concept and 1 sketch thumbnails

I normally start with asking myself some simple questions to narrow down my ideas, like is this creature big or small, does it live in forest or grassland, does it have any fur or scales, does it look robust or elegant? This process helps me to build a description of my creature, and generate a few ideas. I visualise them by drawing thumbnails. Sketching is like an extension of thinking. For that, I only need to draw silhouettes or outlines.