In the introduction to the hymnal Christian Hymns put out by the Evangelical Movement of Wales, they include John Wesley’s rules for hymn singing. I do not know the original source of these but I thought they were interesting. Enjoy!
1. Learn the tunes.
2. Sing them as printed.
3. Sing all. If it is a cross to you, take it up and you will find it as blessing.
4. Sing lustily and with good courage.
5. Sing modestly. Do not bowl.
6. Sing in time. Do not run before or stay behind.
7. Above all, sing spiritually. Have an eye to God in every word you sing. Aim at pleasing Him more than yourself or any other creature. In order to do this, attend strictly to the sense of what you sing, and see that your heart is not carried away with the sound, but offered to God continually.