Freehand sharpening is the best method once you learn.
DMT medium and fine diamond stones is all you will ever need.
I couldn't disagree more that freehand sharpening is best. I will give you that it is an excellent skill. A precision cutting tool is best with a precision generated edge. I worked for sometime at GE in the cutter grinder shop sharpening tools, got fairly good at it with both machines and by hand. But when it came to a long lasting edge it was always best done on a machine. Consistency is key and a machine/jig is going to provide greater consistency.
