What is the guideline for dealing with disbelievers to win their hearts to Islam?

Question:
What is the ruling on greeting a disbeliever with the salam, smiling at him for the sake of calling him to Islam, and being kind to him so that he may submit to Islam? Is that considered showing love for the disbeliever?

Answer:
A disbeliever does not initiate the salam, but he is addressed with kind words: "How are you, so-and-so?" "How are you, so-and-so?" "How are your children?" He is called to peace, but he does not initiate it. However, if he greets, he is to return the greeting. The Messenger (peace and blessings be upon him) said: "Do not initiate the salam to the Jews, but to the Christians." And the polytheist is even less deserving of it. But in conversation regarding the call to Allah, one asks, "How are you?" He asks about his name and about the matters that help him accept the truth. Then he calls him to Allah the Exalted. This is without need for a substitute from the Salaf (the earliest generations). But he asks about his difficulties and about what pertains to the call. He explains to him what Allah has made obligatory upon him, that he was created to worship Allah, and that it is obligatory for him to learn his religion, to understand his religion, and to enter Islam, using good expressions and a good manner.