I use Adobe Illustrator to design my own labels and business cards then print them onto adhesive labels with my laser printer.
You could use Photoshop but, if you have Photoshop (the REAL Photoshop and not "Photoshop Elements") it often comes as a package which includes Illustrator, InDesign and Acrobat. That's how I got mine.
Illustrator is the correct tool for the job, anyway.
I designed my business card with Illustrator and printed them out using perforated business card stock from Office Depot. Then I adapted that design to make my labels. I just downloaded the template from Avery's website and copied the business card file into the template. After making a few adjustments for the different label format, I was done.
It's easy enough to do this in an evening's work, after dinner. I have about a half dozen versions of my design, prepared for different sizes of labels and cards. Everything from return address labels to quarter page stickers. Now, I just go to the store, buy the labels I need and use my ready made files to print them out. I can have dozens of labels, on demand, in just a few minutes.
Forget labels. As others have said, they will fall off. Best is to write the information in pencil. If you are making large editions, use a rubber stamp, but othewise just write in pencil on the back of the print. And no fancy calligraphy, just simple printing except for the signing of your name.
Michael A. Smith
The reasons some may wish to use label blanks, whatever their construction, include enforcement of consistent provenance, lack of good freehand penmanship and formatting, as well as ease of editioning. Inconsistency in process, whether in the lab or during presentation, can be the biggest challenge of any photographic artist.