A quality pair of pinking shears can often be sharpened for longer life. There are several methods that can be employed to sharpen the zigzag edge on a pair of pinking shears. Because they are expensive, sharpening is preferable to replacement for most users.
Fold a large piece of tin foil into multiple layers. Cut repeatedly through the foil, using the entire length of the blades. This will temporarily sharpen the shears.
Cut a sheet of sandpaper. Using the entire blades, not just the tips, make numerous long cuts. The sandpaper grain must be extra fine, or it will cause further damage. Rough sandpaper will pit and scratch, rather than sharpen, scissors.
Take your pinking shears to a professional for sharpening, if other methods don't produce the desired results. Finding a reputable professional is important, because your expensive shears can be ruined by sub-standard attempts with professional sharpening equipment.
Ask a local tailor or seamstress for a recommendation. Check with the clerks at your favorite fabric store. Talk to crafters you know and ask where they take their pinking shears for sharpening.
To reduce the need for sharpening, use pinking shears only on fabrics for which they are intended. Do not use good sewing shears to cut paper, cardboard or extremely thick fabrics, such as denim. Different manufacturers use varying qualities of metal in their shears. Some sharpen very well. Others scarcely sharpen at all.