Good lord...you obviously haven't done it before, have you? Those are pretty common sense questions, I think.
Now, what the client may ask, at random:
How many times a day (but you should have told them that already, anyway)
Any side effects to be expected?
Is it going to make me drowsy, ie: better to take it at night or in the morning?
Can it interfere with any other medication I'm on (eg: the pill)?
Can it be taken whilst pregnant?
Effects of drinking alcohol?
Hope this helps....