Writers search for the truth of any situation, and hopefully this truth will carry over into their everyday lives, making them aware of their own lives. Life teaches and it does this best when those making mistakes learn from them. If nothing is gained from making a mistake then it is counted as a loss. These lessons and understanding them comes with time, life's lessons is an ongoing process and the positive results will be gradual; a person must be up to the challenge.
Using past mistakes as a stepping stone to improvement does not happen simply because one wants it to happen, it happens because an important lesson has been learned. The first step is to be open to yourself and be ready to glean whatever truth is in any error or mistake that you make. Life is full of errors but learning from mistakes lessens them as time marches on. http://stress.about.com/od/positiveattitude/a/learn_from_your_mistakes.htm
The best way to become a better person is to be true to yourself. In fact, work at knowing yourself. An old adage goes, "be true to yourself and it follows as day follows night, you cannot be false to any man" This sounds easy, but it is hard to do. When you can look your self in the face each morning and see the good, the bad, and whatever else is there and accept all of yourself, mistakes and all, then you are on the path to learning from whatever life dishes out.
Criticism is hard to take but 95% of the time there is at least an element of truth in it. Glean that truth and accept the hurt it brings and learn from it. But don't live your life through the eyes of other people, they do not see the real you and are not privileged to know you as you know your self. Accept the applause when it comes but don't be blinded by it. Don't let it usurp your life to the point it is what you seek.
Who wants friends that only tell you what you want to hear. Would you rather have a friend that will tell you the truth about any situation. Of course you would. So consider the people who care enough for you to see you don't take that extra drink, or that you stop being too harsh with your children, or too rude to your neighbor, your real friend.
Essentially what will make you a better person is that still small voice that will tell you no lies about yourself. Listen to it and follow what you know to be true. But don't sit around and do nothing once you find out why you are you, go out and put it to some good use. Share yourself. Help others find themselves. Let them in on the secret of self-knowledge, be true to yourself.
And don't despair. Don't ever give up. Get in the habit of daily meditation and be truthful about what you did during the day that was not up to your best self. Get a good grip on these 'errors' before they become like not kidney stones, but far worse, mental stones that do more damage because they cannot be detected. Whenever you know you have done wrong try to rectify it as soon as possible. Don't leave it there to harden your sense of right and wrong.
The next time you catch yourself being critical of your neighbor, ask yourself why. Then take a good luck at yourself and look deep within and try to see how it reminds you of something you do. When you find out the resemblance to your neighbor's annoyance to your own, you may begin to be more tolerant. It is by these small truths that we learn about ourselves that make us better people.