I sort of just copied COTS and went with a basic RASP. The bigger one is aggressive and removes material fast. The little one is nice for finer work and areas where you need to move slowly.
I also use a hatchet and even a table saw at times depending on how much material I will need to remove. The table saw is mainly just for when I'm fitting a handle intended for a larger eye to a head like the Craftsman in one of my last posts. I draw out my lines for the length of the eye and rip off some material quickly to give myself a good starting point. The hatchet and knife can be used to remove material quickly as well, but you need to be careful with hickory since it has a tendency to tear out. I want to get a spoke shave at some point but reality is that the bulk of my work is done with the rasp and then the palm sander.
I like to mark out the cut I will make to form the fawns foot first and with ink. I then follow that thinning down the sides of the axe, forming a swell, and following the existing curves for the most part on the front and back. I try to spend equal time on each side, and I stop and inspect the handle visually and by hand along the way. You would be surprised at the little imperfections that you can feel but do not see on a handle. Mark them with a pen or pencil and work them with the rasp, even if you've already moved on to finish sanding as I find a lot of my little mistakes at that point.
When all that is said and done and the head is fitted to the head for the final time I make the cut to form the fawns foot by hand. I also sand out the rasp work right near the cut by hand as well. Both so I don't lose the line I drew, and so I don't round off the swell by mistake.
I would take a look at COTS project thread as well, I got a lot of my inspiration to put some extra effort into my handles from him and others. Next big step for me will be sourcing some lumber to start making at least some of my handles from scratch. Hopefully I can pull it off.
