Criticism has been around as long as there has been art of any form. There was a great scene in Mel Brooks' comedy, History of The World: Part I where shortly after the first artist came the first critic who expressed his opinion by lifting up his fur covering and...well, you should see the movie.
The Hard Part:
The hardest part of getting criticism is listening to it first hand. You have just dedicated yourself to your project whether it's writing it, directing it, acting in it, or what have you. To hear someone berate your work is simply never easy to take. That said, it's an opinion that you can either let affect you or you can ignore.
Unfortunately, the rule with anything you do is the rule of thirds: one-third of the people will love you; one-third will hate you (no matter what you do); and the last third won't really care either way -- they might like or dislike you depending on the project. So, if you can't sway 100% of the people 100% of the time, your new rule should be -- don't try to.
If you focus exclusively on creating the best project you can and you pour your passion and every into everything you do, then your chances for success improve dramatically. If you stick to your convictions, you will eventually find that one-third of the people who love your work. And as for the rest -- you need to develop the attitude of, "who cares what they think?"
Don't Let Fear Stop You
One of the biggest obstacles keeping people from succeeding in the entertainment industry is the fear of failure. The fear of being humiliated and feeling like a loser. There isn't a single big name actor or director who hasn't had some failure in their lives. The difference is that they kept going even when the overwhelming opinion of their work was negative. Imagine had Dustin Hoffman simply given up after Ishtar, or Steven Spielberg after the critics panned 1941. Failures teach you more than success ever will -- as long as you're willing to learn from them.
If you feel that fear of failure or being humiliated is keeping you from living your dreams than do whatever you can to break its grip. You have to get over these fears and realize that they are doing nothing but holding you back from everything you want in life. Let it go and don't be afraid to fail.
Constructive Criticism:
Now this piece is not meant to imply that all criticism is useless. There is actually some value in quite a bit of criticism. Take the important lessons that are being offered up within the context of someone's opinion -- ONLY IF YOU AGREE WITH THEM. Remember, just because someone feels a certain way doesn't mean that their way is better than yours, unless you happen to agree.
Learn which battles to fight and be careful not to stick to your convictions simply because you want to prove the other person wrong. If you see that their comments might dramatically improve whatever it is that you're working on, well it might be something to consider integrating into your final product.
Don't let the fear of receiving criticism keep you from going after a career in entertainment. Those who have succeeded in this industry (including me) will tell you first hand, that once they realized that they no longer had to worry about having to have everyone like who they are and what they did, it opened up their abilities to become successful. Never let fear of failure rule who you can become. There will always be those who dislike you and what you do -- let them and remember to tell yourself -- it's their loss.