Make a list and description of those situations where you feel that you need a different way to behave. Describe what you feel in each of these situations: anxiety, fear, shame, etc. Look at the situation from the list and try to answer the question of what they have in common. Perhaps, in all these situations, there are strangers, authoritative persons, etc.
Ask yourself, what is the situation from the list of the most undesirable to you, and which, on the contrary, the most simple. Now you can describe the situation where, for example, you lack confidence in yourself as follows: "I feel certain emotions (what) if (condition)." Example: "I feel tense when I have to speak in front of a large audience of people." So, a clear statement of the problem - it is an important step.
Now that it is clear under what circumstances need to feel different, start to work on it. Let's start with the fact that confident people usually do not experience anxiety and other such feelings. It comes at a time when we are in something uncertain. Then we begin to wonder: "What if I'm wrong? What if they laugh at me? What if I lose my job? ". Often one of those "if" entails all the others and formed a lot of questions that you answer one answer: "It will be terrible." A major step - to find all these "if."
Answer to your question "What if ...". Just not in the fantastic and the real key. In life, indeed it may be that you do not know what to say at a party. But the answer should be: "Nothing terrible will happen, I can always ask other people what they think about something and listen to other opinions." You have to understand that what you see as something terrible, in fact it is not.