Step1
Focus on your positive attributes and achievements. Have a closer look at yourself and concentrate on the good things about you which make you, your friends, and other people like you.
Step4
Apply any or a combination of these strategies:
(a) Look for people who have self-confidence and who would serve as your models. Find out the things that they do/say which make them confident. Then, depending on your values, beliefs, culture, needs, etc., incorporate the things you have learned from them into your life.
(b) Find some self-help resources --- books, seminars, classes/sessions, websites, etc. --- and apply any insights gained.
(c) Have a positive self-talk or mantra.
(d) Visualize and "experience" your expected results. Think, feel, and act in ways you should... once your goals are accomplished.