I've played almost exclusively magic users (although I tend to roll a bit of assassination in there as well), so perhaps my experience will be of use to you.
The biggest thing I can say is - exploit the enemy AI. They tend to be fairly braindead about how they assault you, and they won't open doors or use teleportation glyphs. One time I took a whole zoo down 2 or 3 monsters at a time by using small passages to keep them from surrounding me, and exploiting the fact that they have poor pathfinding. Typically, the enemies would rather walk against a wall than try to find a way around it. When the coast was clear, I'd open my door and walk to the end of the wall, which would cause a few enemies to spill over it. If I walked back into the room and waited a bit, I'd have a manageable clump of enemies to off before my mana completely drained.
I tended to hoard liquor, and buy it from vending machines when I could. However, you can also restore mana by just walking in circles, so if you get into a fight, make a few kills, and are tapped out, retreat. Close a couple of doors, and then you can recover. Knowing where a relatively "safe spot" is can make all the difference.
Skill-wise, I played mostly a mage with some support skills, and this is what I leveled early:
- I really like the Assassination tree. Most of the skills in here are passive, so they work regardless of your current weapon or
mana and have no cooldown. Being able to stun an enemy in a bottleneck so that you can flee, or just do critical hits more often when you're low on mana, is a big plus.
- Get a pet to tank for you. Early in the Promethean tree, you get to summon a wyrmling. This summoned monster is an invaluable tank. Golemancy has similar "monster summon" abilities, if you prefer to have it even earlier.
The Promethean tree also has early-game area-of-effect and damage-over-time in the form of Dragon's Breath. If you lead enemies into a narrow hallway, breathe down the hallway, and then smack the closest one around with Assassination, the other enemies will wander about in the flame patches, softening them up for later. The occasional stun from Blackjack means they're not going to be getting that many hits in.
Crafting and item wise, I tended to have enough liquor to suit my mana needs, but you can also distill many types of liquor to craft mana or health potions if you have the necessary ingredients. In the early levels, when you find rusty equipment, you can grind it down to make one of the ingredients for a health potion for example. Similar rules apply to aluminum gear for making mana potions.
There's kind of an overwhelming amount of different foods. I tended to prefer the Cheesy Omelette, just for inventory conservation purposes. You can use the ingot grinder to grind most types of cheese, and add a single diggle egg with 3 stacks of grated cheese in the ingot press to create an omelette. As my inventory tends to overflow with diggle eggs and cheese, this worked well for me.