I don't know how it is in other states, I've only hunted them in Arkansas, we have three species, the red or fox squirrel and the grey or cat squirrels and the flying squirrels.The fox squirrels are commonly found in smaller wood lots and the edge of larger forests. Hes more laid back than the grey squirrel, he begins his forageing later in the mornings, goes about his business at a much slower pace than the grey squirrels and is a much eaiser target than the grey squirrel. He is also about 1/3 larger than his cousin.
The grey squirrel is quite a different animal, he idles at about 90 MPH
Will begin his day earlier than the fox squirrel, he has a nervous twitch about him, hes always in a hurry, he works tirelessly, burying nuts and depositing them in dens in hollow trees. The excelent photos above of the leaf nests are refered to locally as summer nests.
The flying squirrels are actually gliders, mostly nocturnal and never hunted.
Contrary to some posts above, camoflage is absolutely necessary here, the squirrels have exceptional eyesight, super hearing and apparently are equipped with sensitive nose's as they can retrieve buryed nuts later in the year, even into the spring. They do not require your use of the wind to stalk them however so the ability to relate the oder to a human is questionable.
My favorite technique is a method locally called still hunting, it is best employed after a light rain which wets the leaves on the forest floor and allows a silent approach. I slip from tree to tree, pauseing at each tree to survey the area ahead and to each side, I try to hunt with the sun at my back and at a painfully slow pace, always watching for the swaying limbs that are indicators of a squirrels location, dead clam days are favored, high winds will normally find squirrels on the ground and they are not as sporting to take on the ground. I hunt with either a scoped .22 rifle or a red dot equipped 617S&W handgun. Shotguns are favored by most people but I enjoy the hunt much more with a rifle or pistol. A good squirrel hunter will almost always be a top notch deer hunter, this is my take on squirrel hunting....enjoy the hunt!