First, avoid playing over negative scenarios in your mind in which all of your worst fears are realized. As Freud pointed out in 1925 in an insufficiently appreciated paper, "On Negation," the brain doesn't deal well with negatives. If you concentrate on ways of avoiding a bad outcome rather than bringing about a good one, your brain will lock onto the negative. As every tennis player knows, the surest way of coming up with a bad serve results from energy wasted on avoiding gaffes rather than concentrating on the intended ace. Concentrate on your ideas and your goals rather than focusing on the bad things that could happen, or on how nervous you're feeling.
Or in other words, it's not what you don't do wrong. It's what you do right.