The Prophet (صلى الله عليه وسلم) said: Recite Surah Al-Ikhlas and the two last Surahs of the Qur'an (Al-Falaq and An-Nas), in the morning and evening three times, and it will suffice you for everything . [Abu Dawood and al-Tirmizi]

Abu Umaamah (RA) narrated that:
The Prophet (صلى الله عليه وسلم) said:
"Whoever reads "Ayatul-Kursi" [Qur'an 2:255], after every obligatory prayer, nothing prevents him from entering Paradise except death (i.e. that he is still alive)."
(An-Nasaa'ee, Ibn Hibbaan -- Sahih)