What level are you?
What class(es) are you?
What's your stat array?
What items are you using?
What feats/skills do you have?
WEll as I said, I've tried Monk and Ranger and Rogue so far. level by the time you arrive at the prison, if you go straight there from the academy would be 3-4 by the time you have cleared the streets of the peninsula.
Stats? not exactly min-maxing, but I put most points in the relevant skills, so around 16. Monk uses fists, ranger bows, rogue short bow and short sword. At that low level there's not much to be had in equipment, due to affordability issues.
One of my problems is that the henchmen behave like complete idiots, rushing in even when you tell them to stay close, and pulling in a zerg of 10+ prisoners. Only a couple of times have I managed to clear most of the ground floor up to the first serious mini boss, but then he has quite a squadron hiding in the tunnel behind him and nothing I can see that I can do about THAT. Once they come streaming out, it's game over.
Not been able to take him down yet, with the rogue or with the monk henchman. He slaughters them, and he slaughters my character. One shot, quite often.
If there's a less dangerous area to level up beforehand, that would be handy I think.
It sounds like the biggest issue is tactics and getting swarmed by groups.
Yes. NWN Henchmen are total idiots. Use the radial menu to issue "Stand your ground" command to them a lot to keep them behind you when exploring new areas. That way you can edge into an area and do a quick look without invoking a swarm, and maybe use your bow to pull a couple to you, then run back to your henchman and knock them off easily in smaller numbers (dont' forget to issue an "attack nearest" then).
Low levels are always hard in DnD games. But a couple of points.
It is much harder for Dex fighters early on and that likely includes rogues/monks and probably your ranger from the sound of it. Bows also suck in NWN.
A High Strength fighter (17 can be a good start) is probably your best be if getting back into NWN. Getting Power Attack and Cleave ASAP is good as the payoff is never better than at low levels when you have only 1 attack.