Even if you are never sued and are never a party to a dispute in court, there is nevertheless a reasonable chance that someday you may receive a subpoena or a summons. These documents mean that you will likely be required to go to a hearing and testify on a particular subject, or produce some document or item for the court to consider as evidence.
Much of the time, going to court to testify, alone, is not a reason to worry. You would simply go to court, swear to tell the truth, and testify about what you remember. The lawyer that called you to testify will likely meet with you before court to make sure she understands your testimony. If you don't remember or don't know a detail, there's no reason to feel embarrassed, just explain that you do not know. Don't make up details that you do not remember!
However, sometimes people are called to testify on topics that might get them into trouble later. Everything a witness says in court is recorded and may be used against the witness later. If you have any concerns that your testimony may land you in legal trouble, consult with your own attorney. Although you may want to hire the attorney that called you to testify, it's best to hire a different attorney to avoid conflicts of interest. Your attorney can then review your testimony and advise you about all the consequences. You have a constitutional right that protects you against giving self-incriminating evidence, so your attorney may be able to keep your testimony out of court on those grounds. When in doubt about testifying, the safest course is always to consult with your own attorney.
Just like giving testimony, producing documents or other records named in a subpoena is required by law. If you are concerned that these documents contain self-incriminating evidence, speak with an attorney. Whatever you do, do not destroy the documents. This, in itself, is a crime. You may even get in trouble if you simply failed to save records that would have been destroyed anyway. Instead, give any evidence to your attorney, who will review it and decide whether you run any legal risk by presenting it to the court.
If your testimony or other evidence is not self-incriminating, you are generally required to present it to the court. If you don't, you could be held in contempt of court and forced to pay a fine for delaying courtroom proceedings. An attorney can provide valuable assistance with determining what degree of compliance with a subpoena may be legally required, and whether documents or information being sought might be privileged or confidential.
For more information on subpoenas, see FindLaw's information on What Is a Subpoena?
Contact a qualified attorney.