So, uncertain about your alignment? Here is some food for thought shamelessly stolen from the Endhaven Supplement. (I'm going to assume all of you understand, or can google the basic RPG alignments)
When creating your characters, you should understand what type of characters that the DM wants in his game. This will help the DM get the genre and feel that he wants to present in the game. You will also create a character appropriate to the game before you.
D&D is an action oriented game. Your character will face a myriad of dangers. Your character must be willing to face those dangers. It is up to you to find that motivation for your character.
Focus on the Party
Your character wants to cooperate with others to achieve their goals. Team-oriented characters are the cornerstone of a party.
Some back story is good for the character. Too much backstory leaves your character nowhere to grow. The best backstory is one that helps define your character, but still leaves you room to innovate about your character.
3D Alignment Chart
Instead of a two dimensional chart of Lawful to Chaotic and Good to Evil, add a third dimension of Honorable to Dishonorable.
I won't stop you from playing evil or dishonorable characters, but the rest of the party might do them in prematurely. You have been warned.
In the end alignment is not a straitjacket or a shoehorn. I permit alignment changes that fit roleplay, and roleplay that fits alignments.