Maia,
I agree with what others have said about attitude being the most important tool, and to be gentle with yourself.
I will sometimes tell the beginners lesson that they shouldn't get caught up on making mistakes, we all make mistakes, in fact tonight I will make a mistake to increase their comfort level, if it helps. And although I don't TRY to make a mistake, mistakes happen.
Most recently, I said "ladies chain" instead of "ladies allemande" in a walkthru. "Oops," I said, "I meant allemande. I made that mistake intentionally to show that it's still okay even if you do something you didn't initially intend to do." We continued the walkthru, the dance worked fine, and the light touch signaled not only that "it's okay" but also "be gentle with each other."
On those rare nights when all the stars align in my performance, we don't get those learning moments on the floor. There are good possible outcomes in most every scenario, as long as there's good dancing.
Even when things beyond my control go wrong, I've learned to redirect. For example, if the sound goes wonky, when the sound is restored it's a good idea to acknowledge how much the sound tech works behind the scenes to make most evenings so seamless. Let's thank him/her for all they do. (Okay, I stole this from another caller, but it's come in handy more than once).
--Jerome