Well, if you have two homing phase devices, you can easily skip those levels. Is arch-ville is behind a group of monsters, try to get at his back.
When I have lots of ammo, I just tend to shoot blindly hoping to hear the "Arch-ville pain" sound. That's where my next round of lead will be coming. Remember, that actually only monster that you have to kill to win the game is Cyberdaemon (and one of the Doom's programmers if you are smarter than Hell itself).
Besides, it is always good to die 100 times and find the strategy that best suits you. I for example tend to get eagle-eye, then cat's eyes, and then Son of a Bitch. If I get unique pistol, i pack everything to Son of a Gun. This way, I have at least little control who attacks me (with that traits and unique pistols monsters get knocked back easily). A sidearm is BFG. Good, if it is with magazine mod.
Other people will tend to say, nah, this is useless, you are low onn health, can get killed easily, etc. etc. I am right, and they are right. You have to find a strategy that best suits you!
The main rule is to watch everything what is going around you. Never, never ever try to run using the cursors. If some monster spots you, and you just keep tapping the arrow keys, that monster will get 2-3 free shots at you. At higher level it means certain death.
Watch out for levers. I use them after I finish the level. Sometimes they will spawn monsters (this usually means free xp for you!), sometimes they will heal you, sometimes the barrels will explode. The main rule, when using levers: make sure that barells won't damage the powerups that are on the level and that they will not damage you when you use the lever. And always use the levers, that are near to exit or door, in case that room becomes flooded with lava, you get a chance of escaping.
