I have been using "Allene's Original Tacky Glue."  I dilute it
with about an equal part water.  Apply just enough to cover the
label, using a flux brush.  Wipe of any excess with a tissue
immediately after placing label and nothing will show later.

The label sticks well and sets quickly.  The roll paper/label does
not take on a warp as long as you give it a minute or two to set
with the paper lying flat.  Unlike some other glues, the result
is flexible, not stiff.  Have never had a problem with adhesive
failure, but have only a few years' experience.

Mix in small batches.  I use a cap from a spray can, the kind with
a small ring inside the cap.  Put a small amount of glue in center,
water in the outer ring.  Add water to the glue, using the brush,
until you get the right consistency.

This stuff is available at Michael's Craft Stores and Joanne's
Fabrics, both national chains as far as I know.

Paul Eggert
Fountain Hills, Arizona