Classes
Lets begin with the classes. The NWN manual has this to say: A Class is the profession or vocation of your character. It determines what he or she is able to do: combat training, magical ability, skills, and more. In selecting what class is right for your character, keep in mind what base strengths you want him or her to have. The eleven basic selections can approximate most any character concept.
That last idea is very true. As I mentioned, a good way to make a character is to think of someone, some hero or villain you want to play and use the rules to make that character. It might take a few levels to get your character to where he or she is starting to have the right ‘feel’ for what you had in mind but do not despair. This actually gives a better sense of reality, as no character starts fully formed and perfect. Everybody has to learn his or her skills/spells etc. from the ground up.