Also, help the stalker downstairs; if you go raid the bandits, you can mostly stay out of the fighting (but help so they dont die) And you get even more loot. If you cant take a gun, grab the ammo. Also, if a gun is below about 75% quality, you cannot sell it, and its not cost effective to repair then sell anything that is below about 65% quality. If you bring tools to a repair guy, do the one in Yanov (midgame;) he does not need alcohol to function.

Playing STALKER correctly: Act like you want to aid the bandits at the boat where you start the game, then talk to Beard and side with the Stalkers, You get mad loot, search all the bodies. Then, talk to ppl and do missions. Grab a shotgun and an assault rifle, preferably scoped AK 74. Later, you'll get European and American guns which are better. THere is a Russian LMG, but it is not worth it; hard to get ammo. Snippy Rifles are hard to find, so get a scope for your AK 74. Sniper no sniping. XD Good luck!

How are you settled in?