Sing the songs that actually move you...whether they make you cry or make you laugh...and try to move your audience, to reach their emotions and make them feel something outside of their own lives. If the song doesn't move you any more, the audience won't care about it either. In my opinion, the best public performances (be it music, theatre etc.) is most successful when it conveys emotion and creates emotion on the part of the audience. Everything else is the vessel for the transmission of emotion. Touhing people in their heart is what it's all about.