Here is how I make squirrel:
Heat a heavy pan with a thin layer of oil in it. Put the squirrel in the pan and fry for a couple of minutes until brown - turn over and brown the other side. Remove squirrel from pan. Stir slice onion into pan and cook slightly. Return squirrel to pan, add muchrooms if you want. Season with garlic, salt and pepper. Add enough water to cover the meat. Simmer for at least one hour, I prefer to cook it for two or more in a cast iron dutch oven. This can be done in a crockpot on low for 4 or more hours. Remove meat and thicken the broth with flour and water to make a gravy. You can pick the meat off the bones and mix it into the gravy or serve the pieces of squirrel on the plate with the gravy poured over it. Serve with potatoes - either mashed or boiled.
Squirrel can be very tough and dry as there is no fat on the meat. Make sure to allow enough time to cook it low, slow and moist.