To maintain a knife:
 
 1. Always use a cutting surface made for a knife, like a cutting board.
 2. Don't keep your knives in the same drawer as other silverware, preferably you have a block made for the knife to rest in.
 3. Always hand wash the knife... don't put it in the dishwasher.

To sharpen a knife:
Go out and buy yourself a sharpening steel. When you notice that the knife is duller than usually, sharpen it. To do this, there are a few key factors you need to know:

 1. Keep the sharpener vertical.
 2. Hold the knife at a slight angle to the sharpener.
 3. Stroke downward and towards yourself.
 4. Alternate strokes, and do an equal number of times on both sides.