Having the concept on hand leads to one of the most crucial parts of the process – gathering references. I usually start small with a couple of pictures per asset and grow my library as I go through modeling and texturing.
Once I’ve collected my references, I start blocking out my scene and the camera. This involves simple shapes for quick adjustments. However, you’ll notice that the hero assets are already a little more complex. I start with the most important assets early on, which lets me iterate more on those before the deadline. Blocking out the camera angle and the surrounding scene is a great help.
Source: Unity Technologies Blog