So in his ALS Ice Bucket Challenge Facebook CEO Mark Zuckerberg begins just one sentence the way he prefers to: with "So..." But Zuckerberg can sometimes start a large percentage of sentences with this handy word. Traditionalists deride the "so" speaking technique as a crutch and say its pervasive use subtly informs listeners that the speaker is lazy or unintelligent. So we all know Mark Zuckerberg is about as lazy and stupid as Steve Jobs or Bill Gates.
So English profs might not cotton to your "so" usage, but then again maybe they're not who you're trying to please. "So" at the beginning of a sentence brings the listener in--it's a sort of spoken "in media res" technique used by good writers (isn't that ironic?) to start a conversation (or story) in the middle, as if speaker and listener are already engaged with one another. So it's as if you're continuing what you and the listener began together earlier. So if we had time right now we'd look up how many times Shakespeare did it, which would be more than a few. Zuckerberg, you may say, is no Shakespeare. But Shakespeare probably would have been the best Facebooker of all time.