Observation

 

Switch on all the senses before even taking off.  Make notes on anything you see, hear, smell, taste or hear, even if it's only a web page.

 

Go live on the venue.  Follow the other visitors, their gestures and expressions, weather, issues of anger management, rush, laughter, net promoterness and everything that could not be expected in advance. The most demanding task is to realize what is missing - the true designer skill.