This sounds sanctimonious, but I think always give people a chance. Sometimes the result is a positive surprise, and who needs more "enemies" in the world? Sometimes people have a strange manner and you just have to realise where they are coming from. Also sometimes people throw your niceness back in your face and take advantage of you being friendly and trying to meet them half way, but that only costs a bit of pride and isn`t the end of the world. There`s a French philosopher who has said all that in much less words. I think his name was Yoda, and wise he is.