WEDDING QUILTS - I try to use the same font as the wedding invitation to make my label. I print a label using my computer - then I use Pigma pens & my version of a light box to trace it in the CENTER of the backing. I iron over the label to set the ink. .I plan ahead when I make the backing so that I have a light center in the backing.
MY VERSION OF A LIGHT BOX: I have a sewing table with a recessed 'hole' for my sewing machine. The machine support can be dropped out of the way. I put a piece of glass across the top and a lamp on the floor below. Voila, light box. I tape the printed paper label to the glass, so I only have one thing = the backing = to control while I'm tracing the label.
OTHER QUILTS. I use the same light box, but I usually put the label in the bottom RIGHT corner. Of course, it all depends on where the backing is light enough to use the pens - I have to think ahead when I'm planning the backing. Now that I have an embroidery machine, I'm going to try embroidering labels. Pigma pens are faster, though! And I'm usually doing the label at the last minute LOL