You need to do is build your confidence and self-esteem levels, as these attributes determine how comfortable you're with yourself. The more confident a person is, the easier it is for him/her to mingle with others, and exchange honest opinions with them. There are many confidence building activities that you will find, that can help you with the same.
You need to be sure of the purpose for which you want to change your personality habits and undergo self-improvement and personal development. Outgoing people network better with others, and this helps them expand their career opportunities, tremendously. Some people wish to become more outgoing simply because they want to make new friends.
You should constantly read and update yourself about current affairs and other pressing matters of significance. No one likes a person who is ignorant. Keeping yourself updated will give you the ability to interact with people who have strong and assertive views.
After all, you cannot improve your people skills without actually being around them. Once you are at these places, you can utilize these methods to mingle with others and make friends.
In order to become a more outgoing person, you need to improve your communication skills and develop a sense of positive thinking about yourself. Nobody likes to interact with negative individuals. By changing your thought process, you can easily become more social and make new friends.