I have been playing this game on and off since I bought the retail version of it for 9.99 back in 01' at a Babbages. It was pretty tough when I first started playing it too. That was before I got familiar with the game, it's mechanics, and how to take advantage of certain aspects.
Like the others have posted before me, and it bears repeating: Use turn based mode when encountering monsters for the first time, or in dungeons.
I also have some other pointers:
1. Make sure you learn archery ASAP. This even benefits casting classes, so you can conserve SP for difficult situations.
2. Don't cast spells like Fireball in narrow halls or up against a wall. It's a bad idea. Don't do it.
3. Also bears repeating, level up often, and early!
4. Identify is good to learn early so you save your money for more important endeavors. That 100gp per item does add up pretty quickly.
5. Use the bank. You're gold is all gone when you die and are brought back. It sucks to lose 5000gp after doing something stupid.
6. Read the manual. It's very useful and it can teach you some more basic info you may need!

Castle Darkmoor in general is well, one of the worst places you can be in. There's a quest you can get from the nearby town of Darkmoor which has you going there, along with retrieving a certain item that you need for the Oracle to awaken. That however does not show up until much later in the game, after you've exposed a certain traitor and gotten everyone's approval at the Free Haven Council.

Knights are only good at the beginning, otherwise they are horrible. Having played through this game many times I've decided to go with having at least two Clerics, a Mage and a Druid. Druids are absolutely good at MM6, probably better to have more Druids than Clerics.

Isn't this amazing? quite a few experienced players has come to completely different play-styles.
So my suggestion is to just find out about spells. And definitely get light magic, and light magic expertise early. And also meditation mastery for the character that is to cast those spells, as they take lots of sp.

Speed is really an essential stat for any class, as it increases attack frequency, and defence as well.

Try making a new party of archers:
A + A + A + Cleric.
With as little luck as you can, as you can use the New Sorpigal well to increase it to 15-16.

Then just show the letter to Andover in the tavern, and head to Castle Ironfist to deliver the letter. And get the bow skill for the cleric, and better bows for the whole party (you can save and reload outside a shop to get new random items).
Get some other nice gear as well, but stay away from chain in the beginning, as it slows you down more.
Then head back to New Sorpigal.... and you will see the power....

And brew some black potions, after maxing your deficient stats like luck from wells. As if you drink a potion of luck right away with 5 in luck, you get 20 luck, and you can't increase it with the well. Where-as if you max it with the well, you get 30 in the end.
And you will be cutting through everything like butter.

Edit: I think this and MM7 are the most fun games to replay. Diablo 2 is also pretty great to replay. But I start a new party at least once a year, perhaps even since the time it was released, though I didn't even know how to distribute skillpoints back then (I very young).
Imagine if these games also had some random level generation in it, like some randomly placed dungeons, algorithmically generated. With the scale of Castle Darkmoor (though not filled with liches and eyes, hehe).
If done well, then I could say with 100% confidence that this is still the best first-person RPG. As Oblivion with mods can be really good.

I'm necroing this thread with my reply, but the thread is still on the first page, so no harm is done. I'm very grateful for this piece of advice given, as my first playthrough got stuck for lack of money. I had finished all quests in New Sorpigal, went to the next town (can't remember the name, it's some time ago) where there was a Cultist Temple to be defeated but I got stuck as there was no way for me to heal after combat as I had run out of money. I couldn't buy the stay at an Inn and AFAIK that's the only way to heal.

In that playthrough I had bought better equipment when I could afford it as well as spent money on training, but then I got at a point where the loot of combat was less than the money I needed for staying at an inn and the playthrough got stuck because of that.

So I'll take your lesson to heed for my next playthrough: play just with the items I find. That leaves me still with another problem to tackle, being undecided on what party to take. With every set-up I think about, there's always a different class that I find lacking in my set-up and I end up with wanting a party of 5, but of course, I can't. Maybe I'll open up a new topic with the ideas I toyed with and try again after all. It's just there's Pillars of Eternity to start as well by now. But I'll come back to MM6 one day.

Depending on whether you are willing to take advantage of the NWC dungeon, there is an unlimited amount of money (though you can only get more when you are below a certain total) available, as well as low level equipment.

I'd advise forking over the cash to get a bow for each character pronto, but after that looted equipment can make up most of the rest of your needs.

You don't have to stay at an Inn to heal. A temple can heal you (for a price, varies by temple and whether you'll be receiving status cures as well as hp/mp cures), spells can heal you (Self magic), some fountains can restore hp/mp, and you can rest (camp) outside. When camping, different types of terrain will require different amounts of food; while desert and swamp may require 3-5 food, grass (which may only be a few steps away) can be rested upon for only 1 food. You can get more food from trees (apples), cookpots (sometimes), or buying it at an inn ("Fill your pack to x days") which might be cheaper than staying at the Inn. The only issue with camping is that you might have a random encounter, where some monsters show up and attack your party.

just go to the nwc dungeon grab the boost there and go kill shit in new sorpigal using the temple to heal instead of resting that should send you on your way to godness (make sure you have 1 elemental magic user for ease of access) if you sell literally everything that you get from the dungeons in new sorpigal you should easily have enough to grab a fly book from freehaven and if you use 2 dupers maybe a lyyods beacon spell too at which point the game becomes so easy its almost impossible to die unless you do something stupid

also i dunno why everyone hates on knights i love them typically i use knight archer druid sorc (3 ele casters 1 spirit mind body, 1 light dark) and having a worthwhile tank that dishes out like 130 damage per hit late game (spear sword) before blasters just makes most things go squish specially when backed up by another doing around 90-100 per hit (archer axe and sword) and 2 casting incinerate/implosion and then when normal weapons become useless to you having 2 healers for your hench and a 1.4k hp tank wearing golden plate means you can dish out godly amounts of damage before popping one of the hench

Don't forget, there is a chest in the NWC dungeon you can click to get you up to 10K gold very quickly. Combine that with the loot and you can buy just about anything you need getting started.

I not only like knights, I've played four of them together once or twice. It's difficult doing the whole game w/o spells (except for scrolls, of course), but once you hit around mid-game you have an unstoppable battalion of tanks that can even run over dragons.

im not sure about 4 knights as it would make cave of the dragon riders damn near impossible i have done 4 archers before that was fun considering they have the damage output of knights and the ability to fly /beacon etc as well

also in the nwc there is a book of inferno in the bookcase also which helps clear out those pesky early packed rooms

Easier than you would think, because they have very high HP and damage output.

I have not yet played 4 Archers, or the like. They have the damage output, but neither the HP of Knights or SP of Sorcerers.

I have played 3 Sorcerers + 1 Cleric, and had each specialize in particular schools of magic* so as to maximize their respective skill levels.

* Sorc1: Fire; Sorc 2: Water, Earth; Sorc 3: Air, Dark; Cleric: Self, Light. Something like that, anyway.

I don't believe I've ever found that, and I basically stopped running through the entire place (though now I'll start looking for it) once I've gotten what I want.