All praise is for Allāh, who has created time and has made some times better than others; when rewards are multiplied as a mercy to us. The successful person is the one who makes the most of these special days and hours to draw nearer to Allāh through acts of worship.
Among the special days of worship are the first 10 days of Dhu’l-Hijjah, which Allah has preferred over all the other days of the year. The Prophet ﷺ said: "There are no days in which righteous deeds are more beloved to Allāh than these ten days." (Al-Bukhari, 2/457)
These 10 days are better than all the other days of the year, with no exceptions, not even the last 10 days of Ramadan. But the last 10 nights of Ramadan are better.
Among the good deeds which we should strive to do during the first 10 days of Dhu’l-Hijjah are:
Reciting the following adhkar (aloud and a lot) -
"Allahu akbar" (Takbeer)
"Al-hamdu Lillah" (Tahmeed)
"La ilaha illa Allah" (Tahleel)
"Subhan Allah" (Tasbeeh)
Fasting (up to the 9th and especially on the 9th - yawm-ul-`Arafah)
“The Prophet (peace and blessings of Allah be upon him) used to fast on the first nine days of Dhu’l-Hijjah...” (Abu Dawood; classed as 'Saheeh' by Al-Albani in Saheeh Abi Dawood 2/462)
Sacrifice at ‘Eid
Repentance
Doing more good deeds in general. Praying more nafl Salat, reading Qur’an, making du’a, giving charity, honouring parents, upholding ties of kinship, enjoining good and forbidding evil.