I' ve used lots of different methods over the years, from Lansky kits, to carbide V' s, to whetstones. The method I prefer involves a mill bastard file. It' s simple, cheap, fast, field handy, and does an excellent job. Files must be fairly new with sharp teeth. Flea market varieties are always too dull. I take a small file (~8" x3/4" file surface) into the field, but prefer a larger one (~14" x2" file surface) for use at home or truckside as it covers more of the broadhead and removes metal more quickly.

I start out by making 20 or so forcefull passes (from back of head to front) on each blade edge to remove factory mill marks (in the case of new heads) or dings (in the case of used heads). I keep rotating the heads and making forceful passes until I have a shiny, undamaged edge. That initial edge with still be fairly dull and rough with a burr and file marks. From that point on, I make successively fewer and lighter passes on each blade edge, removing the burr from previous passes and refining the edge. Eventually, I only make 1 or 2 very light passes per edge under only the weight of the file...pushing forward just gently. I repeat until the file has honed the head to perfection, sharp enough to shave clumps of arm hair in a single pass. I stop there if in the field. At home, I sometimes refine the edge further with a suede leather strop, occasionally coated with Brasso.

Expensive and time consuming tools not required. I' ve tried to improve filed edges on an Arkansas stone, but that actually dulls them.

This article gives some good insight:

http://www.bowyersedge.com/broadhead.html