It's fine to credit briefly the writer of a song or the person who inspired you to sing it. Over and above that, sing it and let the song speak for itself. Faffing around in an Irish tune session is unacceptable, as is the use of printed music, yet there are people who can play thousands of tunes without hesitation. If you have to flick through sheets of paper in order to prevent your forgetting the words, your commitment to the song is questionable. As are your manners!