The Practice Blog has some helpful deposition tips.  They include

• Know your state and local rules. And, maybe more importantly, know your local customs.

• Ask open ended questions and LET THE WITNESS TALK. This includes taking a pause after you think the witness is done talking. People want to fill silence and leaving a few seconds of silence may get the witness talk to more and provide you with information he/she may not have otherwise said.

•  Ask the witness who cannot remember if there are any documents that would refresh his/her recollection.

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I would add this to any list of deposition tips:   Listen to the answer.