I was thumbing through a writing book last summer that had a worksheet on creating characters. Basically, it stated that you start with a character and give him a problem.
For example, Tadian has lost his two-dollar bill.
We now have a character with a motivation. Anything Tadian does will somehow be related to his attempts to find his missing bill. As we write scenes involving Tadian, we now have a frame for deciding how Tadian is going to move, react to situations and other characters, and what decisions he’s going to make. We weigh them all against his basic motivation.
Establishing a character can really be that simple at the beginning.