The American Bar Association provides tips which are very useful if you are facing a deposition.  The first one is the most important is to tell the truth. Second, is to listen very well to the question. If you need to pause and think as long as necessary before answering and make sure that you understand the question and don’t answer unless and until you do.  Third, if you don’t understand the question, say so, ask a question or to explain to repeat or rephrase.  Make your answer be as clear and concise as possible.  If you don’t the answer, simply just say you don’t know the answer. If you don’t remember the answer, say I don’t remember.  Make sure though not to confuse saying “I don’t know vs. I don’t remember”.  You can also qualify your answer, by saying something like “I don’t remember right now or I don’t remember without being able to look at this document.