Icewind Dale: Enhanced Edition

When in Easthaven, do the quest involving Jhonyn and the blue-skinned woman and earn a pearl. Return to talk to her (immediately before she disappears) . If you are quick, you can talk to her again while she is disappearing and she will go through the same dialogue -- and you will get another pearl. If you are quick enough, you can get three pearls, each worth 100 gold pieces.

When inside Kresselack's Tomb, past the first big door, will be a Skeletal Mage named Mytos. If you are polite with him, and opt for a nonviolent solution, you will get extra experience points before the fight.

To level up a character easily, have only one character. Go through the first quests at the starting town. Then, save the character as an import. Start a new game and load the import. Do the same quests as if you were using a new character. It does more difficult to level up, but it is possible to get your character to level 22 before going to the next town.