We watched a lot of youtube videos before attempting this on our own for our meat birds.
This is the best item we own for processing. Make yourself a kill cone. Here's the post on here that lists the best one I've seen:
https://www.backyardchickens.com/t/389035/how-to-build-a-killing-cone
This handy little item makes the process a whiole lot easier - the trick is to get the cockeral's head through the bottom opening (many tuck their beak to their chest!). To make ours, we purchased aluminum flashing from Menards - it came in a roll. Not terribly inexpensive, but a whole lot easier than trying to hold the chicken down while cutting throat.
Also, you'll need an incredibly sharp blade to do the deed with. Not kitchen quality - fishing quality (we bought a 4" fishing filet knife exclusive for this deed). I know once the cut is made, the rest of the processing we do with a single-edged razor blade (like using for house projects). This short blade mades it very easy to cut the gut area without danger of cutting into the intestines.
The one thing you need to watch for when you're pulling out the innerds is the gallbladder. This small, dark green projection from the intestines cannot be ruptured - or the meat will be spoiled. It's located on the intestines, so it often comes out with them. Just handle with care to get it into the garbage a.s.a.p! The lungs are tricky to get out. Use your fingers to get up into and between the ribs from the inside as high into the cavity as you can. They're bright pink, so you'll be able to see them once everything else is out.
Lastly, read, read read! This forum is full of tips and tricks to help you. I know how much they helped us! Good luck!