My brilliant Civil Discovery professor offered several tricks for holding depositions, of which he said he never partakes but believes we should know about.
He said he once knew an attorney who cut the legs of a chair. He would trim off three inches on the front legs and two inches off the back legs, so the witness would not only be lower ("So they feel like a little kid"), they would also be constantly sliding off their chair.
And my prof told a story about how he was taking a depo of a witness who was represented by a former student of his. When the former student entered the room, he immediately went to the windows and closed the blinds, as the southern sun was shining towards the chair where the witness was to sit. My professor: "Of course I have no idea how those blinds got open..."