One of the most fundamental pieces of GM advice is that you should never tell the players anything but what they sense with their own eyes, ears, nose, and possibly touch and taste. Don't connect the dots for them. Let them figure out what things mean.

For example, if they're searching a room to look for where someone they chased into it went:
Bad: "You see a secret door release mechanism disguised as a torch sconce."
Good: "One of the torch sconces looks a bit different. It appears to be hinged on the bottom."

Let the players decide that they want to fiddle with the sconce and try pulling it down to see what happens.*

However, this can be taken slightly too far:
"You see an object that looks like a sword, lying on what looks like a horizontal wooden slab supported off the floor by four wooden posts."

* This is a good point to have the sconce trigger a fireball trap, by the way.

Transcript

GM: Angus—the guy who said his clone father was "Mace"—is on the stage.
R2-D2: Mace Windu's clone, got it.
C-3PO: You could just say it's his clone.
GM: No, you have to deduce it from available information.
R2-D2: Like when you tell us we don't find any secret doors, so we know there must be one?
GM: ... Something like that...
GM: Anyway, the guy who looks like Luke, but wearing different clothes, joins Angus on stage.
Mark: {singing} Though you count every sheep//You get the feeling that sleep//Is gonna stay away tonight.
Angus McGonagle: {gargling} gargle-argle-argle argle-argle-argle-argle argle-argle-argle
R2-D2: You mean Luke's clone, Mark?
C-3PO: Wait a sec. The thing that looks like my jaw is dropping in what looks like amazement.