The simplest way to sharpen blades is to use stones. If your'r afraid of damaging your favorite knife, start with your old kitchen knives.

First you have to find the stone. It must be harder than your knife (and there are stones I carve with my knife, they will not sharpen it). And it should have a regular shape. I'll make photos of the ones I use.

Fired clay can do the job, and I made a few sharpening blocks, but I think they're not as efficient as stones to start, because they are rather soft.

Of course, your sharpening tool can be bought.