In many situations, you'll need to approach and meet a person in order to impress her/him. These can be at public places, while the person is busy, or with famous/handsome people who avoid strangers and don't want to talk to anyone. To me, it's insanely easy getting the attention of these people even in the most unlikely situations. In fact - the more "impossible" the situation, it's easier for me to start a conversation. I have many canned sentences, but you will learn that most effective ones come directly out of your mind depending on the situtation.