Studying Quran the top priority

Narrated Ibn 'Abbas: "Gabriel used to meet him (Rasool Allah (saw)) every night in Ramadan to study the Holy Quran carefully together." (Bukhari)

Night Prayers

Narrated Abu Salma bin 'Abdur Rahman: I asked 'Aisha (ra), "How is the prayer of The Prophet (saw) during the month of Ramadan." She said, "The Prophet (saw) never exceeded eleven Rakat in Ramadan or in other months; he used to offer four Rakat-- do not ask me about their beauty and length, then four Rakat, do not ask me about their beauty and length, and then three Rakat.(Bukhari)

Praying in the last Ten Days of Ramadan and Lailatul Qadr – Night of Decree

The Prophet (saw) said, "Search for the Night of Qadr in the odd nights of the last ten days of Ramadan. (Bukhari)
Narrated Aisha (ra): With the start of the last ten days of Ramadan, the Prophet (saw) used to tighten his waist belt (i.e. work hard) and used to pray all the night, and used to keep his family awake for the prayers. (Bukhari)

Observing Itekaf

Narrated Abdullah bin Umar: The Prophet (saw) used to practice Itikaf in the last ten days of the month of Ramadan. (Bukhari)
Narrated Abu Huraira: The Prophet (saw) used to perform Itikaf every year in the month of Ramadan for ten days, and when it was the year of his death, he stayed in Itikaf for twenty days. (Bukhari)

Height of generosity in Ramadan

Giving charity generously in the month of Ramadan is also the sunnah of the Prophet (saw).
(Bukhari & Muslim)