How do you make other people think you're confident?

This is really an excellent question and one that most people encounter especially in the younger years. I certainly did. One suggestion is to focus on other people. Consciously try to engage them and ask them questions which will get them talking. They will never notice your insecurities because you will be bringing them out, and in fact they will think you are quite confident, as a result.

I focus on my own body language.

Look at how the people you admire hold themselves. Then, when you are in stressful situations, make yourself hold your body like those people would.

It is a strange thing, but when you hold yourself in a confidant way, you will feel more confidant.

It’s the imported silk I use for my capes…much more authentic than polyester!

Find someone (or several someones) who you think are confident, and imitate them. Say hi to people, smile at them when passing.

Look ‘em in the eye and don’t stutter when you speak. Use power body language.

Head up, shoulders back, eyebrows slightly raised. Expression middlingly warm.

I agree with @Nullo, @Donald_Trump and @Imadethisupwithnoforethought. I stand as tall as I can, look people straight in the eye and look like I’m interested in that they have to say.
I don’t think you have to wear a cape, but if you do it should indeed be silk or, in a pinch, satin. Maybe velvet if the weather is chilly. @Cruiser knows what he is talking about.

First, best way is to be confident. And for me that usually means being very well prepared for whatever it is that I’m having to face.

Part of preparing, to me, is to dress in a way that makes me feel confident. I want to wear something I feel great in and, for certain kinds of situations, things that make me look like I know what I’m doing, polished and capable and professional, and not in any way weak or subordinate. When I want to feel especially confident, I wear grown-up outfits, not please-take-care-of-me outfits (I save those for when I’m having oral surgery), and things with a fairly firm structure with good coverage, not soft and yielding and exposing. I want something that serves as a support and shield, not something that makes me look helpless and vulnerable. A well-made jacket is a great garment to have going for you.

I am also especially careful to avoid any kind of outfit that I have to manage: things that ride up, slide down, come untucked, spread at the buttons, have zippers that slip, or need any other kind of maintenance. I do not want to have to think about my clothes once I’ve finished dressing.

Once I’ve done all I can do to be ready, then the sooner I can stop thinking about myself, the better. There’s that “spotlight effect” phenomenon whereby people tend to think other people are paying as much attention to them as they are to themselves. In reality (unless you are a major celebrity), nobody is really noticing you as much as you think they are. So there is no need to be self-conscious. Look around and you will see people with terrible hair, poorly assembled outfits, unflattering colors, etc., and realize that they are not the least bit bothered. They probably won’t pay any attention at all to whatever you think is horribly wrong with your looks.

Then just get out there and do whatever it is that you’re there to do: have the interview, sell the product, give the talk, enjoy the party, attend the class, meet the guests, present the report, submit the application, whatever—and think about that and not about your anxieties and shortcomings. If you act like you know what you’re doing, people will think you do.

Finally, here’s one thing that just about never fails, and it’s so simple: focus on putting others at ease and boosting their confidence. If you can afford to be giving support to others, man, you must have it together. Smile, make eye contact, stand up straight, and pretend you’re in charge of helping everybody else feel cool, and I think that you will come across as supremely cool yourself.

Rogers and Hammerstein suggest whistling.

Be confident and let other people think whatever the f*ck they want.

@cliofaye: “I have horrible insecurity issues and lately they’re coming back worse than before but I can’t afford to let people see that I’m insecure like that.”

I know insecurity is very common. However, without knowing a single thing about you, I can safely say that you have no reason to feel this way. You are who you are, and there isn’t a single person who knows shit about being you. Breathe, meditate, do yoga, go running, or do whatever it is that brings you some clarity and peace. In those moments, do you feel “insecure”, or does the mere idea of being insecure seem absurd? If it does feel absurd, work on doing more things that bring about that feeling.

I have a secret: nobody is secure in some kind of “we have all of our shit together” way. So, you are not alone, and you have no reason to feel insecure. Get dressed this morning, go outside, and kick ass.

Don’t confront them as if you needed to explain yourself or prove anything.. Visualize them as an equal then listen to their wisdoms and when the time is ripe, reveal some of your wisdoms. It sounds difficult I know.. But swallow your fear and give it your best and no one (of importance) will see you in a lesser light.