How to apply a vinyl tumbler wrap
Draw a straight line down the side of your tumbler. An architecture ruler or the edge of a table work great for this. Fold back a small section of the vinyl backing. This will expose just a small section of the adhesive. Line the edge of the vinyl with the line you drew on your tumbler and apply that small section. Then using your fingers or a squeegee go side to side along the vinyl as it pushed off the backing. Work slowly and carefully, try to keep the vinyl as straight as possible. Be sure to press the vinyl down really well and burnish really to avoid air bubbles. When you get back to the beginning, overlap the vinyl slightly, burnish with the squeegee so you can see the crease in the overlapping vinyl from the vinyl underneath. Now carefully run a very sharp craft or exacto knife right along that crease to cut off the excess vinyl.