When will my party stop sucking?

[AndyG]

You seem a little light on tanks. Your only real tank is the fighter. The monk is a good damage dealer, but you need another bruiser in heavy armor for up front. Druids are interesting, but they're not tanks, so they shouldn't be in the second position. I'd get either a paladin or a barbarian (or another fighter) for that second position. Half-orcs make really good fighters. You can get their strength up to 20 at level 1, and if you drop their int and cha down a bit, you can pump their con up to 18 as well. Just don't put him in the first position. You don't want him talking for you party.

[Zoltan]

It depends also on stats. CON is really important. Lathander cleric and sorceror are ok. Multi-class your fighter with barbarian. Multi-class your rogue with ranger or barbarian/fighter. Drop druid or cleric and got a dwarven fighter/barbarian with 18 STR and 20 CON. Keep your monk they are interesting.
Keep all your CON's 18!

[Vassago]

I wouldn't drop the Druid. They rock! Between heal spells, summoning spells and the ability to shape-shift, they are pretty tough. My advice would be to drop the cleric and pick up another tank (Fighter, Barb or Pally).

[Magness]

Rankor, sorcerors are awesome. The key is them is to have a good grasp of proper spell selection. Nearly every spell you select needs to be one that you'll use a lot. A great way to "safely" learn how to use a sorc is to play a party with a wizard and a sorc. This way, you can make some mistakes in sorceror spell selection without getting seriously hurt.

Like others have said, focus on area effect spells. But there are a few defense and buffing spells that are worth taking. It's also good to try to take spells that cover the various elements (fire, cold, acid, electrical, etc.) so that you may be able to exploit various weakness of various potential enemies.

Here are the spells that I like taking.

Special Note: I am fond of taking Charm Person initially. In chapter 1, it's more effective than magic missile. Normally taking a spell that loses its effectiveness later in the game is not a good idea. But I find that Charm Person is the exception that proves the rule. By the time that Charm is losing its effectiveness, MM is getting useful.

I don't pretend to call this a perfect list. It's simply MY preferences.

Level 1:
Magic Missile
Charm Person (really useful early, moreso than magic missile)

Level 2:
Web
Mirror Image
Melf's Acid Arrow
Snowball Swarm

Level 3:
Fireball
Skull Trap
Icelance

Level 4:
Stoneskin
Emotion: Hope

Level 5:
Animate Dead

Level 6:
Acid Storm
Chain Lightning
Mass Haste

Level 7:
Delayed Fireball
Modenkainen's Sword

Level 8:
Horrid Wilting