Hah, hmm. Well, see, the game assumes you have the (very good) manual.
So let's see.
For light, if you have a wizard, before venturing into that dungeon, have him enchant his staff in an inn; it will be a permanent torch. You should keep a tinderbox and one, two torches around regardless, you never know - and your wizard might die, after all.
For health, try not to rest. Try to use the Treat Wounds skill. That, and resting, is basically the traditional way. Now, some might call it cheesy, but it's actually a perfectly legitimate tactic and has been in the old DSA rules for a long time before it was revised: bring... bring... umm.
I forgot the name. Bring... uh... see, there's two herbs that cure wounds. One is called... "oneberry"? "somethingberry", yeah. It cures 4 hitpoints, no questions asked, and is very cheap. And then there's the other, in German, "Wirselkraut"; that'll cure like 10 hitpoints, just by eating it. Get some of these and your problems are in the past.
I hope some of the fellows here can tell you the English names, I honestly forgot. But get those herbs.
There's also some healing spellls: if you have a witch her... umm... "witch saliva" or something spell cures disease, restores hp, and cures poison, or somesuch, all at once. And then there's, I think, "balsam salabunde" which ought to be a healing spell nearly all spellcasters are proficient with, which you could also use. However, I consider astral energy more important than hp...
(I said cheesy because it's tempting to carry 50 of those on each character and, when wounded, just eat yourself back to full health. Then again, you might argue it isn't cheesy, but rather, convenient - an alternative to resting.)
Sorry for not being very helpful, it's late. Good night.
edit: every character can learn intuition skills; two skills in that category... one is danger sense and the other I forgot. It's a good idea to always raise both of these on a level up. This will reduce trap-damage by a huge, huge degree as most traps require checks on either of those two skills to even trigger.