Wow, you're going to hear a lot of different ways to do this. It seems that everyone has their own preferred method, and you may have to try several to find what works best for you. I tried:
Chopping with a hatchet/machete -- I seemed to lack the arm strength to remove the heads with one neat whack
Breaking the neck with a broom handle -- difficult to gauge how hard to yank, too light doesn't kill them quick, too hard & you yank the whole head off
Pithing -- tricky to find the exact right spot, and you have to cut their necks afterwards anyway
Until finally I learned that the method that works best for ME is to hang them by their feet, bind their wings with duct tape or stuff them in a cone, and slice through their neck arteries. I use a very sharp knife and cut quick & deep right behind the point of the jaw, through the bare skin there, not through feathers. They "cross the road" with the first cut, although their hearts still continue to reflexively beat, which helps the blood to drain more thoroughly.
Yes you will get several people giving their opinion on how to dispatch a bird so here is mine.
I prefer a sharp long narrow blade works for me like a Fish knife or Filet knife. My technique is a bit more different possibly more safe and cleaner then slitting its throat. Plus the blood does drain cleanly without spraying all over everything. Cutting from the outside through all the neck feathers can be difficult.
I hang bird from legs with hooks. Like tow chain hooks or something similar that when you slide the legs in it holds them tight so they do not kick out. I wear cut resistant gloves, with one hand grab hold of wattles holding firmly I pull beak open insert knife deep into throat cutting artery just below base of skull. Drain into bucket, when the feathers relax on neck and wings drop you can pull flight feathers easy. I like to pull them out first because they get in the way of dunking the bird, easier to fit in scalding pot.
I seem to think 120 130 degrees is the correct water temperature. Any hotter it starts to cook the bird. Who ever dunks the birds should wear long rubber insulated gloves water resistant apron and boots. They sell the gloves at home center stores. I dunk them up and down couple times for 20 30 seconds; this helps get water under feathers. Then hang the bird back up and start plucking. The back, breast, thigh and leg feathers will just rub right off without any work. Smaller flight feathers take a little more work.
Fill a cooler with ice then pour clean water over leaving enough room for processed birds.
There is several form postings on here on BYC how to do this however I have never read were someone duct tapes wings this just sounds like a hassle and possibly just to ease the mind of the person dispatching the bird. If cut correctly bird bleeds very quickly and will not flap so much.
Before I made myself a processing station with cones to hold the birds I used duct tape to hold their wings in place. Just 2-3 wraps around the bird. This was to keep the bird's movements to a minimum, and only because I don't like the blood to splatter in all directions. It also helps to keep the bird from falling off the hook. Even though they're done in cones now, I still hold the head in place after slicing in order to direct the blood into the can below. Once they've finished their spasms I will let go.