I use a file, then to a extra fine Hand held diamond blade and when using the diamond I lay it flat across two edges at the same time but I have it so flat it feels like its just sliding across the edges,, you should feel no filing sensation at this part its only smoothign down the tool marks from the file and preparing the edge for the strop..
3rd I have seude leather that is glued to a flat yardstick about a foot long,, I use this to strop the blades but instead of how I did it with the diamond blade I now lift up on the strop so I'm angling INTO the edge of each blade just a tad (as if it was a single blade broadhead) and then bare down just a little bit so it feels like your trying to curl that edge a bit,,,,, do it about 10 to 20 times while easing up on the pressure each stroke to almost no pressure at all on the last stroke and after you do the other sides of the edges (unless your making a single bevel 3-blade) that broadhead will be ultra sharp.
its my way I guess but it works perfect,,,, if you DON't have the razor sharp edge then you need to start over and re-file the edge until it feels factory to file sharp with the file.
just using a file works great too but its a different technique and the most important thing is you need a really good file,, most people I helped here locally had dull files and didn't know it.