I try to put labels on all of the quilts I give to family and friends. The donation quilts have labels put on by our guild. For my own labels I print them out on the Tshirt transfer paper. Then I can iron them onto fabric. They'll last much longer than the labels written with permanent ink. They also are much neater and more legible.
You can also print labels out on fabric. However, if you do that you need to use clear fingernail polish or some other clear fixative and go over the printed areas. That will make the printing more or less permanent.