These are the precepts that have no prescribed measure: the corner of a field [which must be left for the poor], the first fruit offering, the pilgrimage [to the Temple Mount], acts of kindness, and Torah study. Mishna, Peah 1:1

These are the precepts whose fruits a person enjoys in This World but whose principal remains intact for him in the World to Come. They are: the honor due to father and mother, acts of kindness, early attendance at the house of study morning and evening, hospitality to guests, visiting the sick, providing for a bride, escorting the dead, absorption in prayer, bringing peace between man and his fellow, and the study of Torah is equivalent to them all. Talmud, Shabbat 127a

Tzedakah (Charity)

Do not harden your heart or shut your hand against your needy brother... I am commanding you to open your hand generously to your poor and destitute brother in your land. Dvarim (Deuteronomy) 15:7-11

Nichum Avelim (Comfort the Living)

After Abraham died, G-d blessed Isaac, his son. Bereshit (Genesis) 25:11

Constitutes a great Mitzvah to visit a mourner, to comfort and to enable him/her to express grief. When leaving a house of mourning, it is traditional for the guest to say, "HaMakom Yenachem Otcha (Etchem) BeToch Shear Avelei Tzion veYerushalaim" ("May the Lord comfort you with all the mourners of Zion and Jerusalem").

Hachnasat Kallah (Providing for a Bride)

Constitutes a great Mitzvah to help a bride get married, with financial and moral assistence.

Bikur Cholim (Visiting the Sick)

Constitutes a great Mitzvah to visit the sick, and wish him/her a complete and speedy recovery.

Lashon HaRa and Rechilut (Gossip)

Do not go around as a gossiper among your people. Vayikra (Leviticus) 19:16

Whoever shames his neighbor in front of others, has no portion in the World to Come. Talmud, Baba Metzia 58b

Ma'akeh (Guard-rails)

When you build [or buy or rent] a new house, you must place a guard-rail around your roof. Do not allow a dangerous situation to remain in your house, since someone can fall from [an unenclosed roof]. Dvarim (Deuteronomy) 22:8