Do you want to be seen as a confident person?

Here are two things you can start doing immediately.

1. Don’t hesitate when asked a question. Be quick to reply, even it means that you have to repeat the question back as you think of what you are going to say. The longer the pause the greater the chance you will be seen as less confident.
2. Speak clearly. Avoid um’s and aw’s. Don’t give someone a chance to second guess you with your apparent uncertainty.

Of course it doesn’t hurt to look the other person in the eye as you are speaking. Looking down or away negates speed and clarity every time.