If you would like to become more confident, you need to become happy with who you are. Even if there are some things that you do not like about yourself, you need to accept them little by little. It is best if you would get to know what your weaknesses are and you can do things in order to make your weaknesses your strength.
You can also build your confidence by becoming aware of your accomplishments. The more that you feel fulfilled in life, the better that you will feel in general. Do things that will make you feel better. For example, you know that improving your hair will make you more confident. Do not hesitate to do it so that you will feel more confident to meet up with people.