Although a lot of guys don't know it, most cutting tools come with a self-sharpening feature. Tightening the screw or bolt holding the cutters together allows the jaws to work against each other to remove any nicks, burrs or rust. A few well-placed drops of oil enhance the sharpening effect and also help keep the tool corrosion-free. If I notice that the cutting edges start to dull, I tighten down the center bolt until the blades rub against each other pretty tightly. I then open and close the cutters several times, in effect sharpening the blades. Once I see that I've got a good edge on both blades, I can back off the center screw as needed. This simple maintenance, if done every day, will preserve the life and utility of any cutting tools.