The basic Lansky boxed set is very good (clamp, oil and three stones with guides), as is the Lansky 'turn box' with two medium ceramic hones in it (for field use). If you can freehand like Andy that is a great skill to have but I tend to save my big oilstone for cheaper knives (so I don't wreck good ones!)

If you want to retain the convex edge use a mousemat and fine grade 'wet and dry' sand paper.. Be warned this gets through 'industrial' quantities of paper!! It made my S6 too expensive to use, hense back to good old Lansky.