As part of Pocket Gamer Connects San Francisco 2015, Theresa Duringer, co-founder of Turtle Sandbox, gave a talk about how to design cleverly for VR.
She said that "when people put the headsets on, they look all around them", particularly towards the sky, so it helps to place interactive elements in the sky and around the world so that users can find them naturally.
Focus your gaze
Duringer also talked about the need for visual cues to lead the player down specific paths, either with something obvious like a shining light to focus on, or even subtle cues like following the gaze of an NPC.
She also touched on the fact that "people are getting motion sickness" from playing VR games, so it's important to make sure your game takes this into account and tries to prevent this from happening.
You can see all our videos from Pocket Gamer Connects San Francisco 2015 in this YouTube Playlist.