Aside from a few minimal restrictions required for some character classes, a player is free to choose whatever alignment he wants for his character. However, before rushing off and selecting an alignment, there are a few things to consider.

First, alignment is an aid to role-playing and should be used that way. Don't choose an alignment that will be hard to role play or that won't be fun. A player who chooses an unappealing alignment probably will wind up playing a different alignment anyway. In that case, he might as well have chosen the second alignment to begin with. A player who thinks that lawful good characters are boring goody-two-shoes who don't get to have any fun should play a chaotic good character instead. On the other hand, a player who thinks that properly role-playing a heroic, lawful good fighter would be an interesting challenge is encouraged to try it. No one should be afraid to stretch his imagination. Remember, selecting an alignment is a way of saying, "My character is going to act like a person who believes this."

Second, the game revolves around cooperation among everyone in the group. The character who tries to go it i alone or gets everyone angry at him is likely to have a short career. Always consider the alignments of other characters in the group. Certain combinations, particularly lawful good and any sort of evil, are explosive. Sooner or later the group will find itself spending more time arguing than adventuring. Some of this is unavoidable (and occasionally amusing), but too much is ultimately destructive. As the players argue, they get angry. As they get angry, their characters begin fighting among themselves. As the characters fight, the players continue to get more angry. Once anger and hostility take over a game, no one has fun. And what's the point of playing a game if the players don't have fun?