1st advice for the parent

Shaykh Zayd Al-Madhkhalī رحمه الله تعالى said in his book: "The Causes of Righteousness Amongst the Youth and Reasons for their Deviation":

(The First Cause): The presence of a good role model in the home, such as the father, or mother, or a guardian who is responsible for the care and upbringing (of the child) in terms of the physical (such as food, drink, shelter etc) and spiritual affairs (such as religous and moral upbringing).

This is due to the statement of the Prophet صلى الله عليه وسلم:

"Every child is born with a true innate faith in Islām, then his parents turn him into a Jew, Christian or Magian."

أسباب استقامة الشباب وبواعث انحرافهم ص ٨