The NWN Wiki has a good page about your character's alignment (w:c:NWN:Alignment) and you should read the information contained there first. This page contains information about roleplaying your character according to his alignment.
General advice about alignmentsEdit
Good and EvilEdit
Characters with Good alignments. Describe some key points about the background of this God. Include any details of how he became a God.
Characters with Evil alignments do not go around rubbing their hands together in some comic cartoon character saying things like "I'm evil and my evil plan will bring the minions of darkness to this land." Most evil characters will think that what they are doing is right and just. They will not perceive themselves as evil because (as in real life) they still have to justify their actions to themselves even if what they are doing is obviously wrong to others. Remember, what others do is also equally wrong to the evil character.
Imagine two armies (one good and the other evil) which are both equal in strength. War has continued for years without any side gaining much advantage. However, a rare artefact has came to light to both sides and so they both look for it in the hopes that it might allow them to win. The good baron would say the he needed it to bring victory to their just cause and destroy those that oppose the world order. The evil baron would not (unless he's quite unhinged) say that he wanted it because he must destroy all the good in the land. His arguments would be very similar in fact to the other baron's. Good is right for good and evil is right for evil and it's entirely possible that each would see the other as being the evil ones.
How can evil be good? Giving a starving family food and shelter would be considered good, right? Another point of view would be that giving them food and shelter would make them reliant on someone. What if they were just lazy? Should they be given such things then? It's any easy trap to fall into for new players to go around giving aid to everyone just because they are good. Do you help those that are evil? How would you know? A character's (and non-player character's) alignment is classed as player information and not character information and one of the only ways a character can ascertain the type of person he is dealing with is by figuring out their intentions. This becomes more complicated when an evil character does something that looks as if it's with good intent only because you can't see the hidden agenda behind it.
Lawful and ChaoticEdit
Specific alignment guidelinesEdit
Greedy shopkeepers can fall into this alignment easily. A shopkeeper may overcharge for his wares if he is the only supplier for miles. There aren't many places that pass laws that govern shop prices so the greedy shopkeeper can do that and remain entirely within the law. He is evil though because he is purely thinking about himself and using the local populace's misfortune (not having another shop near) to extort money out of them. Evil does not mean a character must go around killing things out of spite. Our shopkeeper might in fact have a generally good standing among the locals if he can justify to them why he charges too much.