My two things:

• “What’s the order when you go through the door?” writing on notepad, then stopping “So the wizard is in the middle? Okay…”
• We play with maps on a TV and I usually add numbers to the bad guys for clarity in a battle. They were going into a dungeon and ran into six small shrubberies that ate their lunch. Came close to a TPK ‘cause they were cocky. Lesson learned, two rooms later they go into a room they can only see half of. In that half are four of the shrubberies numbered 1, 2, 24, 25. The bard: “Holy shit! There are TWENTY FIVE of them in here?” They were quite surprised that they couldn’t find the other 17 since there were only 8 of them.

You feel you are hidden

It seems like they are telling the truth

It appears to be free of traps/alarms

It looks like they believe you

Do you [insert object interaction here]?

You don’t see anything happen

I also enjoy building tension and then releasing, while occasionally building and then giving them jump scare. I did that recently playing Mothership. Earlier in the session two androids were working on repairing a doodad while the Marine stood watch outside the room. When the Marine steps back in the room they see one of the androids in the chair that was occupied by a body a couple of hours earlier

Marine: What happened to the body that was at the console?
GM: As you think that you turn your head to the left, and that side of the room is empty. You whip your head to look on the right side of the room, and in the corner closest to the door
Marine: I RAISE MY SMG
GM: and you see the body of the lieutenant laying flat on the ground, where the androids had placed it so that the body wouldn’t get in their way

Later, while exploring another area:

GM: Your light cuts through the sudden darkness. As the beam crosses the floor you notice the body that was in the middle of the hallway earlier is no longer there. You swiftly swing your beam left and right, looking for the body. As you turn around the light illuminates a figure standing a few feet away behind you. It’s Rico the Android. As you slowly breathe out, tension leaving your trigger finger, you feel something drip onto your face. You look up as something falls onto you. Roll Panic