I've found myself in several situations having to figure this out on the fly. It felt weird to have this big responsibility of introducing someone to their first VR experience - loosing their VRginity. I like Desi Gonzalez' positive tone here: as public institutions, Museums have a huge opportunity to shape visitors' (first) experiences with VR works. Likewise at festivals, where I must say I have been usually disappointed by the way (mostly volunteer) attendants guided my experience. This was usually due to providing too little context or introduction. Just asking if a visitor has ever done VR before - and providing guidance accordingly - can make all the difference.