(Really well made, thanks Cris.)
Addressing the "sometimes": if a whole sentence has been interrupted, you put a comma and continue the sentence after (i.e. "if you don't do this," she warned, "it'll be wack as heck. So do it."). If it breaking apart two (or more) sentences, put a period (i.e. "if you don't do this, it'll be wack as heck," she warned. "So do it.")I will absolutely come find you and have my turtle come back from the dead to eat your kneecaps (chomp chomp) if you screw this up (: