Be Confident
I will definitely say that this is the most important thing to be achieved to obtain a better personality. You have to be confident with whatever you do. Your confidence says that you know about your work and you are well aware of your abilities. If you shy of speaking in public then you have to start speaking as having confidence is very important. Believe in yourself and to help you build confidence read success stories of other people. Have motivational slogans and pictures on your board etc to help you boot your confidence.