Cerebreus: If in groups, use the shotgun and take them all out at one time.
Crimsom Heads: Use the same tactics as zombies, except if they charge at you, duck in a door.
Hunter: One acid shell to the face. Wait until they are right on you and fire.
Sharks, Snakes, Birds, Bees: Ignore them.
Spiders: Use six shots of the pistol.
Zombie: Use the magnum for an 80% chance of deception. Otherwise, use the pistol or shotgun.