Confidence comes from knowing you are good at X skill. Confidence itself is not a skill you can hone and perfect because it's an emotional result of having something else. Telling someone awkward and shy to "just be confident" is as good as telling a chronic depressed person to "just be happier". Shit ain't gonna happen just by wishful thinking, you gotta do something first.

What gives you that confidence? Well, results. Not imagining what it would feel like to be good at something, but actually seeing and experiencing the results of it. We humans are simplistic, feeling-driven animals and as much as we like to pride ourselves in our intellect we still are vulnerable to something out of our direct control like our moods and feelings.

So, you might be asking, how the fuck do I get the results of being good at something if I'm not good at it? The answer is simple, you have been told it thousands of times and this is gonna be the 1001st. Practice. We talkin' bout practice. You gotta try different shit until something clicks, and then do that a million times, refining it until it's yours. Here's where the "fake it til you make it" advice comes from. The way you get confident is by practicing being confident. At first you will have nothing to support it with, it's gonna be just a febble facade that crumbles under the smallest pressure, but if you do it more and more it's gonna get thicker, stronger, until you actually get results that will be the ground under which you stand. It's gonna be really awkward and feel "fake" because, as I said, there's no such thing as being confident just out of wishful thinking. But the moment you get results and you the product of your attempts at what you think it is like being confident, the real thing will kick in and it will become second nature, something you don't even have to think about.

The first part is the most grueling and tiresome one but if you stick with it, it's gonna smooth out and get progressively easier and easier. You just gotta put yourself through the mud first even if it feels really wrong, and you weird people out or piss someone off. That's ok, it's part of learning. You don't learn how to walk without banging your head on a few table corners.