I played as a melee warrior (sword) and found that if you get the first hit in and keep attacking, opponents tend to do less damage (for melee attacks the passive Stun skill helps).
My strategy against 3 of the 4 guardians in the catacombs was to stand as close to where the showed up when I opened the tomb, then immediately attack them. For the guardian that shoots fireballs I withdrew to kill off the lesser skeletons first, then attacked him (he was tough and I didn't stand still for a long time or run straight at him, but I didn't need to take any great effort to avoid his attacks).
You can use hit and run tactics with a bow (or spell). Poison Weapon would do extra damage with a bow, or if you do not have any poison potions, you could use the Poison Arrow spell.
Meteorstrike can be cast repeatedly fairly quickly, and has a bit of a stunning effect, so even just a level 1 it is very useful.
The Survivor's Curse spell can also be cast repeatedly and quickly on a target, followed by any elemental attack. The effects are cumulative, so even level 1 of the skill is very effective to greatly reduce the target's resistances.
Scorpion traps are quite overpowered, and even level 1 of Deadly Gift would let you take out pretty much any opponent (if you have found any scorpion traps).
You can leave the town and level up a bit. Opponents are weaker and spread out more east, west and north of town. Check George for equipment upgrades whenever you return to town to drop off loot, etc. You may need to invest more in agility to help your chance to hit and be hit. See:
differences between classes (minor spoilers)
or
Early Starter Tips (NON-Spoiler Version) (contains much of the information in the above topic)
Many tips in the following topic (some of which I listed above) will work for any strong opponent, though it does contain spoilers.
Chasing Josie... techniques for defeating Josephine (Spoilers)
