[M]Believe Allah is One in His essence, attributes, and right to worship.
[M]Direct all worship (du'a, sacrifice, trust, fear, hope, love) to Allah alone.
[M]Learn and understand the three categories of Tawheed:
Tawheed ar-Rububiyyah (Lordship), Tawheed al-Uluhiyyah (Worship),
Tawheed al-Asma was-Sifat (Names and Attributes).
[1]Call upon Allah by His beautiful names: Ar-Rahman, Al-Karim, Al-Ghafur, etc.
[2]Know that whatever befalls you could not have missed you, and whatever misses you
could not have befallen you. (Tirmidhi 2516)
[3]Teach Tawheed to your family — the first obligation after the shahada.
(extra):
[2]Make shukr (gratitude) for every blessing — a grateful servant is loved by Allah.
[3]Study the life of the Prophet to see how he embodied tawheed.
[1]Teach your family to say "La ilaha illallah" first and last in life.
[2]Remove any shirk from your home: remove pictures of animate beings hanging, charms, etc.
[1]Say "Hasbiyallahu la ilaha illa huwa" 7 times morning and evening — Allah suffices. (Abu Dawud 5081)