I generally get past the first dungeon "most" of the time, once you get experience it isn't hard to know what works.
However IVAN is one of those games that the better equipped you are the harder your enemies are. This is very important in the second dungeon, leave those great items behind until you need them to defeat something big.
I struggle to beat the screaming guy, my tactic is to transform into a werewolf and beat the crap out of him, also put health potions in cans so they dont break as easily. However I am no expert at this game, I have gotten as far as the dark frog? level a few times.
There are so many little things that you can do to increase your chances in this game, eventually you will figure most of them out.