The Four G's
In the roleplaying campaigns I run, I have adapted what I call the Four G's: the basics behind every character's concept. To make a tabletop roleplaying game exciting, well-paced and interesting, characters need basic motivations that will be the inherent reason why they seek out adventure (an otherwise suicidal pastime to be sure) which is the main focus of any roleplaying game. Adventure does not have to be about just hacking things up or talking to merchants for days on end, but whatever it is that gets player's characters UP AND GOING!
GOLD: At the root of this PC's motivation is a desire for riches. It doesn't matter what game you're playing: riches, as defined in your game, are sought. Whatever will be done with them is the player's own ideals, but the mere fact that it has to be collected should spur most PC's, and the best way to continue this (if ever the PC "has enough money") is either strive for such lofty goals the PC could never reach them, or find very expensive hobbies or tastes so there will never be too much!
GUTS: Your character is out to prove himself in a world which somehow defied him. It might be the PC with the doubts, it might be an entire town who turned their backs on him, or even a member of the opposite sex. This can be proven in many, many ways. There can be goals of conquests: land, monster kills, or truths. You might want to become the best of his or her profession. A character might have such high goals that it might be a spiritual level the PC seeks that will be forever beyond his reach, but the journey which proves his worthiness in his own eyes.
GLORY: Your PC is not so much out to prove something as he is to show off. You may already think you are the best, now you are going to face the world head on and prove it! Everyone will look upon you as a model individual. Students will seek you out. Royalty and dignitaries will ask your council. Children will call your name and bards write about your exploits. In time this quest for glory can be looked upon as unselfish and gallant and others like a braggart or a hog. Perhaps part of the journey will be dealing with how this fame will affect your PC as he grows.
GOODNESS: You may simply wish to fight the good fight, serve goodness in all it's endeavors. You may want to heal the injured or helpless. You may want to free a country of slaves or put down an evil ruler. You may simply wish to do small acts of kindness proving to the world that it exists, alive and well, everywhere. You may seek a peaceful route of diplomacy for those of an evil nature, or may tackle such force head-on with fevor and strength. The quest will surely never end. There will always be evil to smite and wrongs to right!
Final Thoughts: Your roleplaying PC can be as complex, creative, and varied as you can imagine, but without a tie to one of the "Four G's" it will be difficult to explain why she is out in the world, seeking adventure, getting up with a purpose, and always looking to the horizon to meet what life has in store instead of just letting it find you!