We've all felt nervous or shy in situations that we'd give anything to be confident in — first dates, job interviews, meeting your significant other's parents [1], and the list goes on. Unfortunately, the nerves we're feeling inside can end up on display for everyone else to see in the way we hold ourselves, make eye contact, speak, and smile. Fortunately, there are certain ways you can give the illusion of confidence even when all you feel like doing is hiding in the corner. To learn things you can do to fake a little confidence,

• It's been said before, but I'll say it again, maintain eye contact. Don't look at your toes or behind the person's head — you'll only seem scared or disinterested.
• While not applicable in a more serious or somber setting, you can usually get a lot out of smiling often and laughing easily. A little lightheartedness will make you seem comfortable.
• Speak up! I don't mean speak louder; I mean just talk. Answer questions in full sentences, not just with a word or two. Come up with your own questions too. You may think it's better to keep quiet than to say something silly, but most people assume wallflowers think they're better than everyone else, where as most people won't notice if you say the wrong thing.
• Keep your chin up, literally, and stand up straight. Not only is it good for your posture, but also it immediately makes your entire stature look more striking, and having a presence will give you the appearance of having more confidence.

The best part of all these tips is that once you start following them you'll definitely start to feel more confident!

Source [2]