Les dejo el texto que aparece en Burning Wheel: Character Burner sobre Beliefs. Me parece especialmente útil porque por lo general no se gastan en hacer backgrounds :P
Beliefs are a roleplaying aid to help remind players what is of essential importance to their characters. Obviously, these will vary drastically from player to player. Also, they are not necessarily designed to lock a character into a set of strictures but to encourage them to put some more flesh on the bones of the numbers. Often, Beliefs help settle disputes between player and GM, kind of a last defense for all of the irrational behavior that goes into roleplaying. Using Beliefs players and GMs alike can determine if characters are acting fairly within the game or if they are using outside-game knowledge to benefit or preserve their character. Most people hold their survival in the highest priority, but some may have devoted their life to a higher cause—and be willing to give it for that cause. Others lay their beliefs in the bed of vengeance and still others lay theirs in the arms of service. Of course, once penned, this list is not set in stone and is meant to change with time. Characters should start with at least one belief, but with no more than three.
Ejemplo: _This is where the traits, numbers, lifepaths and character history all start to come together. What does this character believe? Well, I need to take a look at the world from his perspective—he is a farmer, a peasant, who grew up tilling land for distant lord in a high manor. Belief 1: The Lord of land’s word is law. Ok, now something to tie into his traits. His father taught him this: Belief 2: If you want something done right, do it yourself. A little clichéd, sure. But this is also a good excuse to get him adventuring. And it will dovetail nicely with the last Belief: Hates Orcs. Orcs have begun raiding in his region, some of his cousins were killed, and his family’s livestock was stolen and slaughtered, forcing his family into debt with their lord…forcing our boy to seek his fortune in the world._