There are certain occasions when it is Mustahab to make Wudu. Some of these are:
1. When one awakens from sleep.
2. Before every Fard Salaah, even if one already has Wudu.
3. When one becomes angry.
4. When reading the Holy Quran from memory (Hifz).
5. When listening to Islamic lectures and when learning or teaching Islam.
6. When giving Azaan or Takbeer or when delivering the Khutbah.
7. When visiting sacred places like the Mazaars of the Awliya Allah.
8. When making Wuqoof on the plains of Arafaat on the 9th of Zil Hajj.
9. When making Sa’ee between Saffa and Marwa.
10. After backbiting and after committing a sin.
11. When visiting the grave-yard.