I do quite a bit of squirrel hunting during the fall/winter here in SW Ontario.
My weapon of choice is a Winchester Wildcat .22lr with a 3-9 power Bushnell scope.
They are such good sport, very smart sometimes, but I've figured out a few tricks.
My favourite tree-rat hunting accessory, besides my gun, is firecrackers (the little ones in paper packages, that will go off in a chain reaction). What I do is I take apart the package, separating the individual firecrackers, and then use them as "flash-bangs". When a squirrel is hiding inside a tree, or "bellying" on the top of a branch, the noise of the firecracker will often psyche them out, and they'll abandon their hiding spot.
One thing that I've had happen (more than once), is to have a squirrel lead me into a trap of sorts.
They'll meander along the ground, staying just out of range, and lead me into a patch of thick brush.
Once I'm in the brush, where I can't see very far or move very fast, they'll make a dash for it, and I won't be able to see where they go.
No joke, this has happened twice, and I think it's on purpose.
Smart little fellas.