The reality is that your credibility is the most important part of your case. Obviously the facts are important as is the law that applies in your case.
However, all other things being equal (which they're not), your credibility is the key. If you are not believable, then a jury will not believe what you have to say. If they don't believe you, then you will have lost your case even before the jury renders a decision.
The lawyer you meet with will consciously determine if your story is credible. He will have questions in his mind during your initial consultation that you must answer in order to make him comfortable that you are credible. Some people, for whatever reasons, may not be believable. Their story may be incredible. The facts may not sound plausible. The facts may not jive with the medical records or other witnesses' memories.
During the question and answer session, the defense attorney(s) are constantly evaluating you as a possible witness at trial. They must evaluate your credibility which they then report back to the insurance company. The insurance company wants to know what kind of witness the defense lawyer thinks you'll make at trial. This is a crucial part of your deposition.
When you are at trial, the jury evaluates every move you make; every facial expression; what you wear and how you testify. Are you shifty? Are you unsure? Do you hesitate? Do you look to your attorney for answers to tough questions? Your behavior and the way you sit and answer questions are under the microscope.
If you lie about one thing, no matter how small, it has the potential to bite you in the butt. Here's how:
There is an instruction the trial judge gives at the end of the case. It is known in legal terms as 'falsus in uno'. It means that if you find that a witness has testified falsely about one thing, then you can disregard that witness' testimony. The logic behind that is, that if you have lied about one thing, no matter how important or how small, how can we believe that you have testified truthfully about the key issues in your case?
If there's something damaging that's going to come out, your best bet is to get it out there yourself and have the ability to explain it away. You won't be able to do that if the defense gets it out of you first.