CRAZY DUMB ZEALOT
When I play a new Doom 2 map, I have the chaingun readied, just so any emerging chaingunners or revenants won't murder me.
If I just know the territory, I'll stick to the boomsticks, as they have the advantage of being able to hit and run.
For panic situations, plasma gun wins. If I'm assaulted unexpectedly, I ready it so I survive. I hardly use it otherwise, because cells are rare.
Against smaller groups (preferably which are far away and easily controlled), I use the rocket launcher. Against hordes which come quickly on me, I switch to the BFG 9000.
If I know the ammo's sparse, I resort to the melee weapons (berserk which is for hit/run and chainsaw which is a bit safer). An example map is the KDiZD boss level, which, thanks to its room-hallway system, works fine for melee weapons.
I was able to kill D'Sparil from Heretic, from a savegame having completed former levels, by flying and toming my firemace (fortunately I had one), and succeeding in killing ALL of those disciples present there. Fortunately, after that, when D'Sparil was uncovered, I was able to defeat him.
So in Heretic, I'd suggest only using the firemace when it's tomed. It's much better as that.
Note that in Strife, the game suffers badly from 2.5d-ness. Even if sentinels (those rounded robots shooting stupid blasters) are high up, a minimissile with its known little blast radius will still severely damage them, because the blast volume is cylindrical, NOT spherical, as probably it is in ZDoom... You don't use ZDoom to play Strife do you.
Automatic Wolfenstein - Version 1.0.1 - also on Android (Updated 28/03/2015)