if it happens, it happens.

like, if you mess up your picking in a gig or something, you need to think of a way that you can make it sound like you ment to do it. for example, you just repeat it again, and voila! it sounds intentional!

other than that, all i can think of other than superhuman's suggestion is to just relax.

when your all tensed up and super concentrating on one thing, its easier to mess up everything else.