[4EVERM-14]

darkgael covered most of the bases. I can only add that standard velocity ammo is the choice for serious accuracy. Some .22's come with a wax lubrciant while others use a grease like lube. Only your firearm knows which is the better. For handgun usually what functions reliably in the gun has sufficient accuracy for the most part. Rifles are a breed to themselves. Sometimes they'll shoot the cheap stuff better then the super-duper extra expensive ammo.
I've had good luck with Aguila, Federal 900, Eley and RWS.