First, a few words of caution. Present-day sharpening and grinding implements include a variety of electric-powered wheels and abrasive stones. Great care must be taken when using power equipment. In inexperienced hands, these grinders and sharpeners can do more harm than good. Most power sharpening and grinding devices produce a great deal of friction, which generates very hot temperatures. Overheating will "draw" the knife's temper, thereby ruining the blade, which will never hold a keen edge again. There is a danger too, that an inexperienced person may grind away too much of the blade.
The safest method for the average person is to use a sharpening stone. Keep the stone wet using a honing oil or any fine grade oil. Holding the stone in one hand and the knife in the other, keep the blade at about a 30-degree angle to the stone. Start at the knife handle end of the blade and, in a sweeping motion, rub the stone against the blade to the tip. Turn the blade over and sharpen the other side. Maintain an even pressure and the same angle consistently throughout the sharpening process.
To test if the edge is completely sharpened, run the blade edge lightly over the tip of your fingernail. If the blade slips at any spot on its edge, continue to rub the blade against the stone a few more times.
For a razor-sharp finish to your blade, you can give it a final stropping on a strip of heavy leather rubbed with jeweller's rouge, which is a polishing powder. Many sportsmen carry a sharpening steel with them to touch up the edge on their knife between proper sharpenings.