To finish off the "Where Am I Going" step, we translate the encounter into a "foot in the door" to gaining class skills. This is (as previously mentioned) generally by apprenticeship. The character may meet a like-minded individual who takes the character under his wing, and begins their training. Or, the character may seek out a mentor on their own. Using the example of the corrupt fighter (Character Three), perhaps the youth is sent to clean cells or cook for the temple's prison guards, and is befriended by one of the sergeants, who becomes a mentor. Perhaps, in the same situation, the guard makes "over-friendly" advances to the youth, and another guard takes the youth under his wing to protect him. The possibilities for an imaginative mind are endless.
To use an example of developing skills independent of a mentor, the zero-level character rules in the Greyhawhk Adventures published by TSR used a percentage die to determine success at skill-based actions. If they rolled high (like 95% and over) they had the use of the skill at sixth level of ability for a short duration. EG Darius tries to pick a lock, and rolls a percentile die to determine success. He rolls high, and picks the lock, and remembers how to do so for a week. This is described as 'insight', and provides a method for learning skills outside of the traditional apprentice-style learning, and may be good for a skill-based RPG. Although it may appear difficult to create a character this way, it provides an alternative to the 'I was trained by Hum-Dinger the Nifty, and The K-Mart College of Wizardry' type character.
These characters are often good models for a lone-wolf type persona, such as an Artemis Entreri, but can also be very limiting to play if done haphazardly. Most of the characters that are created via this process would tend to be nature priests, rogues, fighters (barbaric) or hedge-wizards.
Last thing to do here is to get these life events, 'defining elements' and career choice into a format you can use to roleplay. The simplest way that I have found to do this is to get a plain piece of paper, and make three boxes on it. Label them Mannerisms, some Favourite Quotes and Motivations .
In the Mannerisms box, write down some of the traits your character has. These can be anything from scratching his chin whilst thinking, always eats breakfast standing up, never sleeps with his boots on, always cleans his sword after combat with a piece of blue cloth, doesn't wear green clothing, and can't concentrate without holding his holy symbol (or sword hilt, or dice).
You can extend this to include some of the character's quirks. To use a modern example, these could be things like not stepping on cracks in the pavement, refusing to buy processed cheese, always having ketchup on hot dogs instead of mustard and so on. In a medieval setting, these may be a fear of horses (perhaps the character was thrown as a child), paranoia about pickpockets, refuses to start the day without a shave, and what ever other foibles you can think of to make the PC more real to you and the other players.
For my character Yusef, I will have him dislike authority figures (after his family's treatment at the hands of the guard), never leaves the house without his weapons, never walks on the right hand side of the street, and can't think clearly without his helmet on.