Likely, you have given depositions out of court, or in court as a witness. But being a defendant in a courtroom is a very different matter.
 
Two key factors are: to be fully prepared, and to be very mindful of your demeanor. As discussed regarding your courtroom testimony, the jurors have a favorable presumption which you don't want to lose that.
 
Be sure to set aside time to not only prepare, but to compose yourself and be rested. In a video deposition consider what you wear. Depositions usually run a few hours to a day, and occasionally can spill over to 2 days. The length of time depends a lot on the style of the attorney. Be sure to ask for breaks when you need time for composure, thinking, or to discuss matters with your counsel.
 
Adopt the posture of an advocate for your cause, defending and representing your own personal interest. Remember that once in the deposition your lawyer has essentially no role. He can prepare you, but then you must deliver. Objections at a deposition are usually reserved until the time of the trial.
 
Your speech should be clear, paced, and calm. If you would like to make an effort at improving your speaking without going overboard, the book "Voice Power" by Renee Grant-Williams is recommended for a few manageable, very effective tips.
Speak as if to patients more than to attorneys, because the jury will function at the patient level.
Try to maintain the same style and demeanor in cross examination as in direct examination.

Key points for you when you testify.
1) Review anything put in front of you, particularly medical reords.
2) If a hypothetical question is asked, you can answer this patient was not hypothetical. I would need to see the patient to answer.
3) Don't express an opinion, deal with facts. Don't guess or speculate.You can answer "I have no opinion."
4) Don't bring or cite any particular paper.
5) Don't interrupt the question, as the last word may change the meeting.
6) Avoid citing a test or reference as authoritative, as some portion of it can be used againt you later.
7) Don't give the deposition in your office or the hospital, becuase other material there can sometimes be used in the deposition. For example a book or journal may be cited by the plaintiff's attorney becuase it is in your office.

Consider basic issues in tactics of the plaintiff's attorney.
The plaintiff's lawyer wants you to sit in a deposition and feel guilty. Instead visualize that you are in a plaintiff lawyers office, not neutral territory.
The point of the deposition is to lessen your credibility with inconsistencies.
 
1) One prominent Plaintiff's attorney stated that in depositions he starts at the meat, asking “Do you have a memory of .." regarding a particular visit. The answer is usually no, and now you are stuck with what is in the record. The attorney has foreclosed your memory.
2) Another common approach is to ask what was on your differential diagnosis.
And another is to quiz you on basic pertinent anatomy to rattle you, or look for a mistake.
3) If they ask: What have you done to prepare, what documents have you looked at to prepare for today? Did you do any literature search? This also is a potential trap. If you need to go to the literature to research subject matter, talk to your attorney first. Some defense attorneys do not want you to search the literature. If the source has a sentence that contradicts your opinion, you have admitted an expert opinion against you
4) What sources do you consider authoritative? A good answer is: I do not consider any source authoritative. What I consider authoritative is the sum of my training and experience,
5) Ask questions to see if your knowledge base is adequate, and also if you are approaching it like you would in the case at issue. Some lawyers will spend more time on general medical principles than specific facts of case.
6) If they find a button in you they can push during the deposition, they will likely push that button at trial.
7) The plaintiffs attorney will not ask questions in deposition for issues they wish to avoid, and plan to bring up later.
 
What if you misspoke in the deposition? There is a provision for making corrections. But the caveat is that the lawyer at trial can comment on the change asking the jury to make an inference.
It is better to set records straight sooner rather than later. Also, a change in the deposition can be cited as testifying outside of the deposition, and then you may be called back for a further deposition.
How do you know what is accurately transcribed? Point it out if you think a transcription is in error.

A variation on the depositions are interrogatories, written questions from a lawyer to the adverse party. Answers are often poor, but these are signed under pain and penalties of perjury. They need to be as carefully considered as deposition answers.