Answered by Sayyidi Habib Umar bin Hafiz (may Allah protect him and benefit us by him).
Please give us some guidelines for calling non-Muslims to Allah
The foundational principle is that, as an expression of your servant-hood to Allah, your heart is filled with mercy and compassion. You then go forth calling people to Allah in obedience to Allah’s command, focusing on the state of your heart and having good dealings with them. You should present Islam to the non-Muslims through your states, your actions and your words.
After that there are various methods that are not mutually exclusive. We should use all the available means, and not use some and neglect others. Precedence should be given to certain methods over others according to the place in which you are calling and nature of the people and according to what Allah inspires you to choose.