Say you all of a sudden woke up one day, and instead of being in your bed, you wake up on the ground right outside the gate to Vault 101.
All you have is the clothes on your back (most probably PJs), a Pip-Boy on your wrist, obviously the knowledge you've gained from playtime, and lets throw in a 10mm Pistol with 2 clips.
Now, you don't have to find your father or anything, there are no quests. Just picture yourself to be there, Its hot, barren, dangerous, and unfamiliar.
You stand up, and take a good look of your surroundings. What would you do from this point onwards?
Edit: Suicide is frowned upon ( But if that really is what you would do, Im not gonna stop you. ).. Oh and, don't hesitate to incorporate any skills you might have in real life.
Eg: Good at Science? Head over to Rivet City, and ask Doctor Li to be your mentor.
Enjoy working as a mechanic? Tag along with Tinker Joe, to wherever he goes.
Stuff like that.