This common sense advice remains the very best recommendation for any witness taking the stand. When testifying, do not try to "argue" your point, dodge questions to avoid problem areas, or place any type of "spin" on your version of the facts.
... and wait until the entire question is asked.
Many witnesses are so anxious to cooperate and to provide quick answers that they don't wait until the entire question is asked. Wait until the lawyer asks the entire question before starting your answer.
Answer Only the Question That Was Asked
If you listen carefully to the question, you must consider the scope of the question and not go beyond the issue at hand. Don't volunteer facts that were not asked for, particularly on cross-examination where -- if you're a litigant -- you'll be volunteering for the other side.
Take Your Time -- Think Before Answering Each Question
There are no points for fast answers. Witnesses who take their time to think about their answers are perceived as being conscientious and concerned about telling the truth. On the other hand, if the prosecutor asks whether you killed your wife, you probably don't want to pause too long!
Witnesses are not "human computers." Many of us have difficulty remembering what we had for dinner last night, to say nothing of events which may have occurred months or years earlier. If you don't know or remember particular facts, do not give your best guess as to the answer. In the hands of a skilled advocate on the other side, guesswork can provide just the tool needed to destroy a witness' credibility and leave him limping off of the witness stand
NO Pretending ... to understand the question!
Ask for Clarification if you don't understand a question - never attempt to answer a question that you don't really understand. Particularly in the anxious and adversarial atmosphere of the courtroom, certain questions may not make sense or may get lost in the commotion of objections. Don't try to make sense out of the question yourself. If you don't understand a question, ask that it kindly be repeated or rephrased. Otherwise, you may unwittingly answer the wrong question, providing the wrong testimony in response.
Cooperate ... but don't placate
You should be cooperative in answering questions and should not show antagonism on the stand. But it's not your job to please your questioner (unless, of course, the lawyer examining you is your own). Cooperation and courtesy do not require that you give what the questioner may think is the "correct answer." Don't be forced into an inaccurate answer on the witness stand
Keep Your Emotions in Check
If your emotions revolve around the aggravation of the trial process, keep those to yourself. Don't Fight show anger or impatience with the process -- after all, the jury is also being forced to endure great inconvenience to sit in the courtroom as well. On the other hand, if you deny killing your wife, emotions can sometimes make or brake you.
When testifying, be consistent with your earlier statements in the case, deposition testimony or testimony in earlier proceedings. Those who give testimony at odds with their earlier statements leave themselves vulnerable to attack and may be perceived as lying even when they simply don't remember relatively minor details. Review your earlier writings, statements and testimony very carefully so that you may testify in a manner consistent with earlier statements and eliminate such attacks upon your credibility at trial.
Try to Relax on the Witness Stand
This advice is easier said than done. But witnesses who appear relaxed and conversational do much better than those who get frazzled easily. While this is not always easy to accomplish, witnesses who review the facts of a case very carefully and who "practice" their testimony with their own attorneys or the attorneys calling them to the stand usually find the process much less intimidating. These witnesses are then able to look the judge and jury in the eye and convincingly tell the "truth, whole truth and nothing but the truth."