Fine sandpaper cures troublesome shifting
Many dovetail jigs (and other types of fixtures) rely on plastic or metal guides that clamp to your workpiece. Despite your best efforts to tighten the clamps, that slick guide may not stay precisely in place on the smooth wood surface, especially when you're pushing a tool against it.
Cut a piece of fine sandpaper (maybe 220 or 320 grit) to fit the side of the fixture that contacts the workpiece. Apply adhesive, such as 3M's 77 Spray Adhesive, on the back of the sandpaper, and attach it to the fixture. The sandpaper provides friction, reducing the chance that your fixture guide will creep out of position.
—Ty Powe, San Dimas, Calif.