Returning to the ways of Torah and Mitzvot in general will bring it about “Today, if you will listen to his voice.”
The Talmud says that if Israel will keep one Shabbat properly, Moshiach will come immediately.
By virtue of Torah they will return to the Holy Land and be gathered in from the exile.
Acts of charity and kindness
Equivalent to all the other mitzvot, “Tzion shall be redeemed by justice and her repatriates by Tzedakah”.