Correct Your Posture: First and foremost, looking confident requires your body to also appear that way. And you can't look confident with a slouching shoulder. Make sure your back is straight and your head is held up high whether you are standing, walking or sitting.
Look Up: Ensure that you when you speak to people you are looking them in the eye. However, if you are struggling with confidence and find it hard to look people in the eye, simply look at the middle of the other person's forehead. It gives the illusion of you looking directly at them without you making proper eye contact.
Dress up: There is nothing that looking fabulous can't solve. If you look great, you'll feel great and radiate confidence. Put an effort in your outfit and you won't be disappointed.
Speak Slowly And Keep It Short: Conversation can be tricky. The simple and easiest rule of thumb to follow is to simply speak slowly and keep it simple and short. The more rapidly you speak the more there are chances of you stumbling in a thought while speaking. Bonus tip: if you want that added oomph, simply ask a question and patiently hear the response. This works best in a group.
Smile: Smiling is essential to look confident. Of course, this doesn't mean grinning from ear to ear (that would be weird and awkward). You should have a light, polite smile on your face that shows that you are open to conversation and will not attempt to bite at the first chance of human interaction.
Take Deep Breaths: If you are fretting over something or the other, the simple thing to do is take five deep breaths. It is a wonder what this can do to calm your nerves and let you continue radiating a glowing aura.