If you aren't confident, gaining confidence is pretty difficult to do, but t's essential, especially because of talking in language lessons, and getting marked on it for English. Even if you don't feel confident inside, it's always best to look as if you are. The secret of being confident is the way you act towards others. Stand tall and don't act scared, just nonchalent. While walking through the hall, stand up real straight and look straight ahead(w/ the exceptions of looking where you're going!) rather than sulking your head down pretending your not there because you are!. You are a person sharing your home(earth) with everyone else. Everyone may not look the same, act the same, or feel the same way, but we are all human beings and are just as equal to anyone else in this world. Don't let anyone tell you're not good enough or are a dork or geek because just because they are miss popular snob witch doesnt make her any more special than you. Always remember that and you will feel equal to or superior to everyone else and be fine. Always remember to smile and keep a positive attitude. If you're always saying bad things about yourself you're not being confident. You need to feel good about yourself to feel confident. If you ever need a confidence-boost, just think of all the great things about yourself and make yourself feel good. If you like yourself you feel confident to put yourself out there and express yourself. People admire people that are confident and able to express themselves no matter what people think.
Remember that if it's a speech or something, other people have to go through the same thing as you which isn't so bad! If it's just walking down the street just think to yourself, 'If they find fault with me I don't care. I'm happy with myself and I can find a hundred things wrong with them if I need to,' It sounds corny, but it should help you feel much brighter!
You shouldn't be afraid to look people in the eye, and talk to them straight. Don't keep looking down! It actually makes the person uncomfortable! Also, try not to make any unecessary movements etc. that will make you look awkward and scared. If you really do need to do something with your hands so you won't randomly fidget, pretend to fix or adjust something you are holding or just hold on to your bag or purse strap or put your hand in your pockets.