What’s the most important rule in VR? Never make your users sick. In this exploration, we’ll review the essentials of avoiding nausea, positive ergonomics, and spatial layouts for user safety and comfort. The Oculus Best Practices, Designing for Google Cardboard, and other resources cover this issue in great detail, but no guide to VR design and development would be complete without it.

http://blog.leapmotion.com/ergonomics-vr-design/