There are hundreds of thousands of  ways to increase confidence level. This is the simple and easiest way to increase confidence. Just follow the technique mentioned below:

Set the sentence ''I am a confident person'' as the password for Facebook, Gmail, Yahoo, Twitter, etc. After a few days you will feel you are more confident than before.

How does it work?
If you directly say ''I am a confident person''' to yourself,  your conscious mind will simply reject it. But if you use it as a password frequently, your conscious mind won't filter it. So it enters into your subconscious mind and then it works.
Discovered by +Don Prince