You need to buy a double sided water stone and a steel and learn how to use them. The stone for regrinding and the steel to hone. I have used all sorts of steels (I had a commercial kitchen and am a chef), coarse, fine, round, oval, ceramic, and I have just purchased a Global diamond steel. It is expensive, but good.
You need to sharpen the knife before the edge goes off it. I also have an electric ceramic wheel that runs in a water bath. I only use that every 6 months and only when all the knives need grinding. I have to put a big sign on the wall or staff get cut
There are two ways to sharpen a knife on a steel, well three actually.
1. the way I don't use. Put the point of the steel onto the board with the
steel vertical. hold the knife at 25 to 30 degrees to the steel and put the
heel of the knife (the bit by the handle) and draw if towards you. Move to
the other side of the steel with the other edge of the knife alternately 6
or 8 times.
2. Holding the steel and sliding the point down towards the hand that is
holding the steel. Make sure your thumb is wrapped around the handle of
steel alongside your fingers, and not wrapped fully around the handle as you
would hold a cucumber. Start with the heel of the knife at the tip of the
steel, and run the blade down from heel to tip towards the handle of the
steel, and your fingers! Again 25 to 30 degrees and 6 or 8 strokes.
3. The way I favour. Holding the steel the same way, you stroke the knife
away from you. The heel of the knife starts at the handle end of the steel
and is stroked from heel to tip along the steel away from you.
Only one person should sharpen and knife and the plan is to be so proficient
at it, that every time you sharpen the knife, the same angle is achieved
every time. If you have a friendly butcher, ask him if he will show you. He
might also agree to undertake 6 or 12 monthly grinding of the blade.
If you really don't want to use a steel, there are electric sharpeners with
a vertical slot you just draw the blade along, but be careful as they can
remove a lot of metal. You can also get a small thing that is made of steel
material, that looks like a fixed pair of scissors. You run the blade along
it. The best way is stone and steel.