Party Composition

In all three Baldur's Gate games you will need at least one of each of the following classes in your party (including multi/dual-classed characters):

• Fighter: There's a lot of combat in both games, and someone needs to be on point to dish out and soak up damage.
• Thief: Traps and locked doors abound, and only thieves can safely and reliably take care of both.
• Cleric or Druid: To heal your party and provide other defensive spells. In particular you need a cleric for spells such as Remove Fear.
• Mage: To identify items and provide offensive spells.

In BG2 you will probably need two mages as you will encounter lots of enemies protected by powerful spells which can only be brought down by other spellcasters. In all games you ideally need two characters who have a reasonable number of healing spells, I'd suggest a single-class cleric and then another character who is a cleric or druid but can be multi/dual-classed.

If you want an 'easy' first play of BG1, generate a fighter as your main character and recruit Kivan, Jaheira, Khalid, Branwen and Imoen. This will give you three strong melee fighters, two healers who can also put up a reasonable fight and a thief for sneak attacks and archery. Don't bother with an subtley when it comes to fighting, just close in and kill everything (mages first, then archers).