Self-education
Insecurity may be caused by your low level of education. If you feel other people are more intelligent and smarter than you, you should try and change this situation. Luckily, there are plenty of ways to do this. You can join some school, enter a college or do this on your own. Self-education is not less efficient if you stay patient and dedicated. Watch documentaries, listen to lectures online and enjoy audiobooks.

Try out martial arts
Some of us are afraid of facing confrontation hence they feel insecure and less confident around people. There is no need to try to get yourself into conflicts. Avoid fighting. We think that people need martial arts so that they could learn to defend themselves and others rather than attack and hurt people. Join kickboxing classes or any other sports and techniques that are related to self-defense methods and practice your skills together with your instructor and other fans.