I tend to have several different projects on the go at the same time, encompassing all of my genres. That way, if the dreaded block appears while I am writing one of the stories, I can normally switch to another and continue with that.
I also have ideas and outlines for another four books already in my head so if the worst comes to the worst, I can start on one of them as well.
If I am ever truly blocked and can't write anything sensible, then I just pick up my kindle and read. That normally gets me back in the mood for writing.