Embarrass yourself.

The writer must be in it; he can’t be to one side of it, ever. He has to be endangered by it. His own attitudes have to be tested in it. The best work that anybody ever writes is the work that is on the verge of embarrassing him, always.
–Arthur Miller

I think this very much applies even, or especially, to critical writing. Anyway it’s something I definitely strive for, and a rule of thumb I use to gauge when I might’ve done something good (i.e., when it seems almost embarrassing).

(Speaking of embarrassing, please pardon Miller’s mid-twentieth-century pronoun usage.)