Find Megaton, along the way, loot Springdale (although you may not be ready for the school yet) and sell the loot in Megaton. Then once your in Megaton, find Moira Brown, who your going to sell the loot to, and work with her on the Wasteland Guide. She has some quests that won't kill you if you pay attention to what your doing. Those quests get you out in the world and get you a few levels. Along the way to Minefield if you first go generally North slightly Northwest, you will see a Junkyard, in there is the best follower in the game, just don't jump into the battle, he can't lose during this. Once the battle is over, then you can recruit the follower or not.
After you work on the guide somewhat (don't have to finish it), then you can decide if you want to chase after your Dad, or ignore that and do something else. Also, in Megaton is a quest that is easy to do that will get you a house in town. Talk to Simms.
Fallout 3 is a game about exploring. And since it is your first time playing the whole world is new. Enjoy it.
Do you have the DLC's as well.
There are not that many quests and some are hidden are never really shown. Explore the game world.
One of the merchants in Megaton has quests that are quite useful.