After experimentation, I think I have learned how to best use my arsenal effectively, choosing the right weapon for my battles to minimize damage.

-The fist should only be used with Berserk and on Demons and Spectres.
-The chainsaw is best used against Demons and Spectres, and maybe Lost Souls who come too close.
-There's no reason to use the Pistol when you pick up another weapon.
-The Shotgun is best used against weaker enemies who do not use hitscan weapons. such as Imps, and for long range sniping.
-The Super Shotgun is best used in close range against lone tougher enemies who do not use either explosives or hitscan weapons.
-The Chaingun is best used against enemies with hitscan weapons, including the undead enemies.
-The Rocket Launcher is best used for long-range or medium-range against tougher enemies.
-The Plasma Gun is best used for tougher enemies or crowds of them.
-The BFG is best used for the largest crowds and the toughest enemies.