No, I don't trap Red Squirrels for the tails, pelts or meat. I trap them because my hazelnuts are almost ripe and a few squirrels can strip every bush I have.
The traditional free-standing set uses roofing nails but I could not find my box. I improvized with fencing staples. My first attempt was too narrow. The key point is that the nails/staples are INSIDE the wires. That is because the wires move outward and then together when the trap is triggered.
The second tweak is to use a file to sharpen the wires of the trigger whisker to make it easy to impale in-shell peanuts on them. Impale the peanuts with the suture line oriented perpendicular to the whiskers to minimize the risk of the nuts splitting when the squirrel tries to wrestle them off the whisker.
I also greased the dog and trigger to make the release smooth and positive. This was not necessary but it made me feel better.
The last few tweaks are to put the trap on a log. Squirrels prefer to travel along logs when they can. Secure the trap to something higher up.
Tie some surveyor's tape to the coil of the spring so you can see from a distance if the trap fired. Since you secured the trap by tying to something higher, the trap will be dangling down after firing. With a little bit of thought, you can arrange it so you can tell when the trap fired.
Squirrels are semi-social. You want to reset as soon as possible so you can catch any of his buddies.