Always be kind, strike up random conversations , pay compliments to strangers.
For me its a natural thing to do and I am always being asked why I do it.
Well I have always done it since a was very young, its just a natural reaction and sense of wanting to help people feel appreciated or noticed.
The smile on someones face, or the light in their eyes when they have had a nice word spoken to them makes it worth while. It costs nothing and we can all do it.