Like 8t, I don't like to talk about the wind. If I say something like "it looks like the wind may lay", it'll surely get stronger just to spite me. Another thing you never do is brag about how good the fishing's been to a friend. If you do, it'll surely be bad when he goes with you.
I had a dear old friend that believed it was bad luck to catch a fish on the first cast. I'm just the opposite. I think it's a good omen because if you don't catch one on the first cast, well then you can't catch one on every cast.