Is this for a bankruptcy debtor's exam (The 341 hearing), or a debtor's exam to enforce a money judgment?
The bankruptcy "Debtor's Exam" is actually non-eventful for almost all debtors.
The only time that it becomes an issue is if there are problems with the schedules (so if you declared or failed to declare something on your schedules, or if you later found that there are problems with your schedule that you need to amend).
Other than that, the trustee will simply go over a few of the things on your bankruptcy schedules, (basically ask you to confirm the information that you have already disclosed), reiterate that if you receive inheritance or certain other types of income within the 6 months after your discharge you must notify the trustee, and then you are done.
To prepare, it is usually a good idea to go over your schedules, make sure that you have provided the trustee with whatever documents they have requested (usually 3 years worth of tax returns), and bring appropriate government issued Identification.
See this link for more information on the bankruptcy debtor's exam: http://www.san-jose-bankruptcy-lawyers.com/how-should-i-prepare-for-my-meeting-of-the-creditors-after-filing-bankruptcy/
On the other hand, a judgment debtor's exam is more thorough, the judgment creditor should have sent you a paper requiring you to bring documentation (such as bank statements, tax returns, etc.) with you, and can ask many far ranging questions about your assets, income, and liabilities (basically nothing is off limits as long as it deals with your finances). You will be sworn in in front of the judge in the courtroom, then, you, the judgment creditor (and/or their attorney) will go to another place, such as the hallway or a meeting room, and they can ask questions which you must answer under oath regarding your finances.