Make it Up.
Talk to the storytellers first to make sure it's kosher, and then just make up details about scenes.
'Mud on the carpet - he wasn't much of a boot-wiper.'
'You smell that? Ugh. Someone nearby hasn't taken their trash out recently.'
'Eagle up there.' Gestures upwards. 'Coming in and out of the clouds.'
Crouches down. 'Heavy smoker. Second-hand clothes. What am I looking for?'
Details that are unlikely to affect the story can be made up with storyteller permission. If you feel like you may have made up a detail that is too plot relevant, you can inform the storyteller and they can decide to either retcon it or weave it in to whatever they're doing.
Get A Cheat Sheet
Ask the storytellers to generate a short cheat sheet of things your eagle eyes might uncover in locations that will come up in the game. To avoid metagaming, these should be short and without context 'in the blue apartment, strange patterns of white grease on the ceiling', 'very faint dueling scars on the hands of the gunman', 'the ship's captain's fat isn't real, it's stage padding and makeup'. Specific enough to know the place or individual when it comes up in the game (if it comes up), but not specific enough to give away plot.
Ask players to pass you a note before the game if there is something about their character you could notice - provide a list of examples, like a change in demeanor, a change in dress, a recent wound, a new concealed weapon, a change in attitude towards another character, or other things that they feel you could uncover with your super senses, auspex, what have you.
This works best with experienced and generous roleplayers as both other players and storytellers, like most dramatic techniques, where things can be rolled back if need be without fuss but still allow for those cool 'I can see things' moments for the auspex-focused vampire player.