The major advantage of this kind of hearing is that the other side will not be present there. They will not have an opportunity to testify or object to your testimony, and the judge will make the ruling based solely on the Plaintiff's testimony and any evidence presented.
If you are the Plaintiff who is supposed to be testifying at such default prove up hearing, makes sure that your attorney spends sufficient time with you, rehearsing your testimony and making sure that you know what to expect and how to testify, so that he is able to elicit all the necessarily information for you in court the best and the most effective way possible, in order to prove both your special damages (wage loss, medical expenses, out of pocket costs) as well as general damages (emotional distress, pain and suffering, etc.).