How to get someone to the good path who is not leading a good way of life?

If i want to get someone to the good path, who is not leading a good way of life, what should I do and where should I begin? Many of my friends do not have much understanding of life and they often make so many mistakes. As I have learned about the consequences of untamed words and actions, I fear for them and I want to know how to get them to listen and think about their own stupid actions. Are there any Theravada teachings on this matter? And/or do you have other advice (all answers are welcome and I am happy to learn every perspective)?