Of the mannerisms of the believer (Episode 20) is that the believer consistently greets others, both friends and strangers, with the greetings of salām.
This greeting is a du'ā for your brother, and a declaration that you desire nothing but peace & good for him. It is a mention of the name of Allah and a bringing of barakah into our lives.
The Prophet (SAW) was asked, "Whose Islam is the best?" He replied, "The one who feeds the hungry and gives salām to those whom he knows, and those whom he doesn't know."
Yasir Qadhi