The most importan thing for a Wizard is his spell list. This describes the type of munchkin effects you can deal out to people. There are some simple rules for selecting the skill complement that you should have:

Rule One
Attack good. Defense not so good. Healing bad (What are clerics for?). Anything else is abysmal and really not worth having. This rule should be pretty self-explanatory. You want spells with either fwackoom people, stop you being fwackoomed, or ideally reflect an enemy's fwackoom back onto him and his mates.

Rule Two
Flashy pyrotechnics. This is very importan. Who gets remembered; a wizard who feackooms someone with silent invisible flame, or a wizard who lets rip a huge gout of rainbow-colored fire while creating a sign out of moonbeams which reads "LOOK I'M FWACKOOMING YOUR KING" as a clap of magical thunder rolls around the land? We know who our money is on. Pyrotechnics scare people, increasing the intimidation effect of your magic and allowing you to keep whole groups of superstitious locals or guards out of your way.

Rule Three
Fire good. Ice okay. Wind wussy.
Your fwackoom spells require a medium to work in, and you usually have a choice of elements. The best is FIRE! It looks cool, it burns people, and if you happen to have a telekinetic in the party, you can work together to produce a pre-cooked self-delivering meal.
There are also uses for the number two element, ice. It can allow you to freeze oceans so you don't have to worry about getting your feet wet when you cross to another continent and you don't have to trust boats. It can also be used to keep rations fresh and to check pools of water for waiting monsters.
Wind is so fundamentally pathetic as to not be worth mentioning.

Rule Four
Seemingly subtle and boring spells can be hideously abused by a competent munchkin into producing all manner of munchkin effects. Examine each and every spell carefully to see if you can spot a twink-worthy loophole. There are moral bonus points for demonstrating that some innocuous "non-combat" spell can be used make people's heads explode. For example, there's that dinky little spell that produces a pint or two of drinking water. This is supposed to be used by idiots who get stuck out in a desert without enough supplies. But check; does your rulebook say where this water can or cannot be produced? If not, how is that ogre going to feel when his brain suddenly has to share its skull-space with a pint of water?
Similarly, slowing or entangling spells rarely worry dragons much. But will they work for just a few seconds on a flying dragon? If so, don't forget the sound effects:
"neeeeeeeoooooOOOOOOOWWWWWW-BOOM!"

I think so. Is that so wrong?

Examples:
CONTEST DERIAN AS CHAMPION OF MOONDANCERS
CONTEST DERIAN AS CHAMPION OF MOONDANCERS
CONTEST DERIAN AS CHAMPION OF MOONDANCERS

Shouldn't he try to get back into the swing of the ever changing combat system before he does that?

I'm here now aren't I?

No soup (credits) for you.

Examples:
CONTEST DERIAN AS CHAMPION OF MOONDANCERS
CONTEST DERIAN AS CHAMPION OF MOONDANCERS
CONTEST DERIAN AS CHAMPION OF MOONDANCERS

No! No, bad! Bad!

Tuek, shoo! We're almost poised to take over the Wilde!

Heretic, get thee from the Light!

Shouldn't you be trying to recruit him?