Good advice from Labrador99.
My advice is know your text thoroughly. By that I mean read the text re-read the text and re-read the text. From your numerous readings create your own notes. The better you know your text the more able you are to apply that knowledge to the unexpected question.
If it is the mini-essay question - there is no way of guessing it. Preparation, Preparation is what you need to concentrate on.
Remember in the critical essay question - unlike Poetry - there will always be a character question for drama and prose. You just won't know what the point of the question is.
The text is King. If you really know your text you will be ok.