The best is to gain focus first: take a white page and write down exactly the behavior you want to change. Take a specific life situation and describe in detail how you behave in that situation.
Take then another white page and describe the way you would like to act in this situation.
Take a real example and write in detail your answers.
Next step is to train yourself in this new behavior. The best is to be extremely aware next time you face this situation. Observe your emotions, feelings and what is happening in you. Then try to act according to what you feel is your best behavior in such situation.
Another option is to simulate the life situation you described and train your new behavior. The key with training a new behavior is repetition. It might not flow and feel really awkward in the beginning. Very soon though, you will notice how you new behavior starts growing and taking roots in you.
Enjoy!