The three-day period should be spent in contemplation of the faith of Islam...

The three-day period should be spent in contemplation of the faith of Islam, recitation of the Noble Quran and supplications, and anything else which can draw a person closer to Allah (Glory and Greatness be to Him). If a person has missed prayers, he should try and make them up in this special period. If he has a clean slate of prayers, then he should try and recite the recommended prayers.

Other than this, all other spiritual acts of nearness to Allah (Glory and Greatness be to Him) should be maintained. However at the same time, one should not do things that keep him busy with the transient world that he has turned away from for these three days – meaning that reading things that would keep his mind busy with work, school, etc… should be refrained from. In addition, all other things which are commonly used to “kill time” should be completely left for this short three-day period.