What are the facilitating causes and means that help a Muslim to perform Qiyam al-Layl (night vigil prayer) easily, and prevent him from being overcome by Satan and having Satan urinate in his ear?

Al-Ghazali, in "Ihya' 'Ulum al-Din" (Revival of the Religious Sciences), mentioned accessible means for performing night vigil (qiyam al-layl), dividing them into apparent (dhahirah) and inward (batinah). The apparent means are: not eating or drinking excessively, not over-exhausting oneself during the day, not committing sins, and not neglecting the siesta (qaylulah). To these is added: not staying up late after the 'Isha' prayer except out of necessity. The inward means are: soundness of heart from malice and innovations (bid'ah) and worldly concerns, fear accompanied by short hopes, knowledge of the virtue of night vigil, and love of Allah and strength of faith in communing with Him.