Here are some threads on that very subject:
1) David the Developer recommends wand mastery, lightening bolt, Mage Armor and getting the Companion Grissenda. See
here.
2) Some discussion on problems with a mage, with solutions. See
here.
3) Some more discussion
here.
4)
Here's one person's end game mage (staff user)
You can search for "Early mage" or "mage" and finds dozens and dozens of threads on this subject.
They tend to boil down to a few basic points:
Skills:
1) For skills, get lightening bolt and mage armor. The first is the easiest elemental spell to use and works well against undead (which populate first few areas). Mage armor is very useful against traps and early enemies that get too close.
2) Lessor Summoning is nifty, even for non-summon builds. That pesky little imp can help you find secrets and traps, plus holds his own in early melee.
Weapon: Staff or Wand?
3) Endgame Staff use does intense damage output but wands are considered more defensive and might be better for a player struggling. Wands also allow one more equipment slot for totems and orbs to be used in the shield spot. If you use wands, invest in the skill Wand Mastery.
Companion:
4) Get Griss. You can get here very early (Level 1 to Level 3) pretty easily. You find her one map away from your starting map. To get her, you just need to dash in and grab a ring. You don't have to kill anything, but clearing a path to and from the ring will help. Just be nice and give the ring to her. She will help with crowd control.
Traits:
5) Expect to invest heavily into INT, and PERS to increase mana use. AWA is useful, too. Some points into AGL and END can help. Not much point into investing into STR .
