If you're asking yourself how to cope with criticism, you must be considering the criticism unpleasant. To cope with criticism, you just need to change the way you hear it.
If I told you that you were "too ethical," would that make you feel bad? Probably not. You'd probably wear that bit of criticism proudly. Since it's not unpleasant, you probably don't even consider it as criticism.
If I told you your "hair isn't brown enough," would that put you in a funk? Many people would simply dismiss it as a pointless comment, especially if you don't have any reason to care about what I think. Though it may be a criticism, who cares?
However, if the brown hair comment comes from the casting director for a major movie role you're dying to land, you'll probably hear the criticism loud and clear. Still, it probably doesn't make you feel bad. You just ask, "How brown does it need to be?" and you run straight for the Clairol counter at the drugstore.
In the last case, the criticism turns out to be something you accept, knowing you have the power to correct it. Coloring your hair for that ingrate of a casting director is a pain in the tush, but you're not beating yourself up over how brown your hair is. Unless of course, someone else with the perfect brown hair gets the role.
Now let's say your boss tells you he's not going to recommend you for that management opening because you're "not aggressive enough." How you respond now depends on how you feel about yourself and how important the promotion is to you.
If you've been hearing for years that you're a wimp and it's an aspect of your nature that you've always hated, and now it's costing you a promotion, you may find yourself running straight for the Vodka counter at the drugstore.
On the other hand, if in your mind he's totally wrong, you'll either try to change his mind somehow, or you'll eventually change jobs. Granted, you may feel disillusioned, hurt or angry along the way, but one way or another you'll change the situation.
In any situation where you receive criticism, either you care, or you don't care. If you don't care, there is no problem.
If you do care, then the criticism is either something that you believe is true, or you believe is not true. If it's not true, then is there a consequence to someone believing it? If it's not true and there's no consequence, then ignore it.
If it's not true, but there is a consequence, then prove the critic wrong. But leave anger out of it. Be cold, dispassionate, and insistent. You won't change anyone's mind by screaming at them, but you may if you can marshal your evidence. If you can't change their opinion, go around them.
If the criticism is true and you care, figure out what you need to do to change. It may be difficult and it may be painful, and you may not want to, but if you don't want to hear it any more, figure out how to change.
Finally, if you care and it's true, but you can't change it, then embrace it and accept it.
Personally, I've been told I'm overly emotional. Bring me a flower, and I'll get all choked up by the sentiment. At one point in my life, I tried to change that part of my personality. It didn't work. So now I embrace it as who I am. If someone else doesn't like it, that's his or her problem, not mine. I've accepted it. They should, too.
So to cope with criticism, simply recite the Serenity Prayer: "God give me the serenity to accept the things I cannot change, the courage to change the things I can, and the wisdom to know the difference."