x2 on JimB's method. I use sand paper on a true/plumb surface via his advice. I start with wet/dry 220 then 320 600 1500. I was going to get 2000, but the local store didn't have it. They seem plenty sharp without the 2000 and I have drawn my own blood several times checking the sharpness. Mirror finish, super durably sharp.
My only advice is to give yourself a reference as to where the head is in the jig so when you repeat the process next year your angle is close if not the same. It does take some elbow grease to establish the bevel angle sometimes, but after that the finer grits go quick.