In answering this question I cannot do any better than citing one of my earlier answers here:

The first ten days and nights of Dhul-Hijjah are considered some of the blessed days in Islam.

Let us refer to the sources to discern what is unique about these days/nights:

1- Allah has made an oath by these nights in order to stress their significance. We read in surat Al-Fajr, “By the dawn and the ten nights.” (Al-Fajr 89:1-2)

According to the vast majority of mufassirin (commentators of the Qur’an), the expression ‘last ten nights’ refers to the ten days and nights of Dhul-Hijjah.

2- The Prophet (peace be upon him) said, “There are no other days good deeds are the most beloved in the sight of Allah than those done in the first ten days of Dhul-Hijjah….” (Al-Bukhari))

It is, therefore, important for us to consider these days as auspicious occasion for excelling in virtuous deeds, according to the best our abilities. To list some of these activities meriting great blessings and rewards:

Performing voluntary acts of worship; Allah Almighty says (in a qudsi Hadith), “My servant shall continue to come closer and closer to me by performing the supererogatory acts of worship until I love him and when I love him, I become his ears with which he hears, his eyes with which he sees…. then when he calls upon Me, I will answer his prayers.

The optional acts of worship mentioned above can include any good  including offering extra nawafil or optional prayers, charities, honoring and serving one’s parents, fostering ties of kinship, rendering acts of kindness to neighbors, fellow Muslims and fellow human beings, helping those in distress, visiting the sick, taking care of the orphans, and the poor, etc.

In fact, good deeds in Islam can embrace any and every act that is beneficial to human beings or the creation of Allah. The Prophet (peace be upon him) said, “The best of mankind is the one who is most helpful to God’s creature.

Fasting in these days merits greater rewards; fasting on the day of Arafah is even more highly recommended. The Prophet said, “Fasting the day of Arafah, I sincerely, hope it would expiate the sins committed in the previous year as well as the one that follows it.” (At-Tهrmidhi)

Last but not least, this is the most auspicious time to seek repentance, make istighfar and establish constancy in dhikr.

In conclusion, it behooves every Muslim to come closer to Allah by utilizing the most auspicious occasion of these blessed days and nights.

Almighty Allah knows best.