Pistol:
the pistol is best used at short ranges,corners and staircases but be careful as these have very low ammo and you can lose track of the ammo therefore aim for the head, overtime you will be able to aim better and get perfect quick headshots.

SMG'S:
sub machine guns are best used in medium-short ranges, in short is best for masses and hordes of zombies and when aim is hopeless and you just need to take care of some zeds before you get overrun, for medium range it is best for when there are individual zombies and headshots or small bursts of fire,
SMG's are also good for quick fire and have a higher rate of fire therefore you should use them on masses and hordes best ( short range) or last resort.

Sniper's are best for when zombies are not yet a threat,good for headshots and clean kills, you klnow the rest lol