Again, there are no rules!
I usually hand embroider my labels. I put the name of the quilt, date made, who is was made for and my name. Some people include the place where the quilt was made also.
I have put sayings on the labels of two quilts.
Another quilt's label was written out with a sharpie pen! As I said above, no rules. Whatever you are comfortable with. My sewing machine will be writing my next label, I think!