Hope that helps, and hope I see you writing on B/R soon!
Well, quite frankly, I'm a bit of an amateur when it comes to this. I never took any journalism classes or anything—I'm actually an actor. I am, however, a sponge for sports information, particularly when it comes to baseball and soccer.
My advice would be twofold. First off, know what you're writing about inside and out. Obviously, you'll make the odd good-faith mistake. I just made a diagram in my Italy/Spain preview that put some of Spain's midfielders into incorrect positions. But don't ever write something in ignorance. Know your subject matter as best as you possibly can. Second, don't try to write "professionally." Write how you write, because that's your voice. I once had an English teacher in high school say that I write the way I speak, and I think that's a virtue. Now, obviously if you swear a lot in everyday life or something (I'm guilty of that), you should redact that. That's really what I can say right now.