I try to follow 3 simple rules:

1. Don't push

2. Don't Push

3. Don't push



Now with that said. simply live life in accordance with the Qur'an and Sunnah. Don't be a Muslim BE a Muslim. Let him see more by example than by words. Be available to answer any Questions, be honest with your answers. Do not say anything negative about his faith. You do not need to try to prove he is wrong, you only have to show you are right,



Always remember Surah 2:256 also remember only Allah(swt) can cause him to revert. All you can do is be honest and in the right place at the right time.
Be patient and avoid being judgemental. Do not allow yourself to get angry.