I think I might help you.
I tell you a little about me:
My case is different to most people here I guess. When I was 19 I started going out alone but didn't go well (extreme AA, bounced because I didn't reflected confidence when doing approaches, etc.). My lack of success with women has never been because of my looks or confidence, It's just been that I never really learn how to act with girls, I had no experience at all. I had no female friends. So I stopped going out and that's it. I had some kind of depression (of course I went to movies, house parties a few times, never to clubs/bars, etc.). I use the word depression because I'm sure that is what it was, although, back then I didn't know.
I was happy just surfing in the morning (every fucking day), being in my room (no one bother me because it was in the office of my father) reading, watching surf streams, playing Counter Strike (only game) and, fortunately, not addicted to porn (jajaja). I did this like 6 years, really. I would still be a virgin if I didn't had the luck that some girls make it really easy for me to make things happen.
So, I was happy, well, I thought so. After those years I started thinking I had to do something. I wanted to be with girls I really like, and not to be with any girl that pops into my existence (the girls I had slept were fine at least). I started thinking that I couldn't understand why I couldn't be with really hot looking girls: I am a good looking guy, I am a good person, I am smart, etc. I started thinking of so many things I got going on with me as a person that I knew that i could be with any girl I wanted (as I always thought so). As you can see, my confidence was not an issue, but, I knew my lack of experience with girls was almost none, and it was my Achilles tendon.
So I started to approach and talk to girls and guys on different places to be social (I knew it would help). I started with people working at stores, models on some activation events, taxi drivers. Then I started to talk to girls on the street (just to do it, didn't expect nothing). During this few approaches I figured out that the best line to open girls walking on the street was to be direct, and, as unbelievable as it might seem, the first girl I open directly in my life ended up sleeping with me (and happened to be the hottest one I had fucked, a beauty pageant contestant). I stop daygame because I thought it was weird (stupid).
After this I startet to go to clubs/bars. The first time, just with my fundamentals (gladly, they were really good already) and my eye contact (I had discovered the idea of using elite eye contact) I could not believe what I was seeing. It was like I was honey and the girls were bees, really. I was amazed. Of course, the AA still was in me and couldn't do anything, jaja.
Eventually I search for PUA again (I had found about this years ago when a friend told me to read 'The Game'. Nice book but I didn't like the whole acting, lines, to pick up girls so I didn't care) because I thought it's methodology surely had evolved in so many year. That's how I found PUAs that rely on a style that appealed to me: Natural. So I digged in!
I read everything and gave me a good knowledge of what to do. To me this was a lot to take in but I think of myself as a natural guy (because I have discovered things by myself in so little time) that, for personal issues, never exploited it.
I know I'm different from many guys because I have always been pretty confident in myself. I know I can and deserve beautiful women. I just wanted to tell you my story to let you know that changes can be made when you really want to and that confidence is so attractive to girls.
So, regarding your question:
… how do you get this sort of airtight self image? All the naturals I've seen tie things in to their personality, as I saw in one of the posts earlier made by Chase. But how exactly do you do this?
It's hard to do so when you are not confident in yourself, because of your looks, or your personality. The first thing to do is to believe that women are not attracted to looks like we do. Yes, it helps, surely, but it's not what will make you get them. So, believe that, really believe that good looks is not the important thing.
The second thing is to improve fundamentals. I really believe you can still attract and make connections with girls without good fundamentals, but it helps to have them sorted out.
They have to be worked on a daily basis.
• Walk/Posture: Go to youtube and search for male models walking on catwalks. Find a style you like and practice in your house (if you have a big mirror great). Then walk like this. Think, think, think. It will be eventually natural.
• Slowness: This should be practice at the same time as walking. You should walk slowly. Take your time. People of high status take their time. Think James Bond. Really slow your pace, a lot. You may think you look like you are stone, don't bother about it. Do it. Everything. Moving you head, arms, etc. (this is a fundamental I have worked on, I did everything kind of fast)
• Voice: You should also speak more slowly if you are not yet(this was one of the fundamentals I didn't had. I talked damn fast). Take your time, pronounce your words.
I have read here about making your voice deeper, having a purr, etc. I really don't care about this but, if you think your voice is kind of feminine for a guy, try it.
• Fashion: I always had good sense for it, just lack of money, jaja. If you don't know about it, ask a friend that does or start looking on internet for styles you like and ask for advice (to be sure it would be good for your type)
• Gestures: Use them when talking and keeping the slow rhythm we talked about.
It's not that hard to do this stuff. Before you leave your house you are covering fashion.
Then, when you get out you should focus on walk/posture/slowness. Is not that hard to practice all of them at the same time because the three are part of the same action: walking
When talking you just have to concentrate on voice. Then you can add gestures/slowness if you can't do it along with voice at the start (I'm pretty sure you'll be able to).
This will get you to other level, that's for sure. Really. Remember what I told you about the time I go after so many years to a bar with just my fundamentals and having the girls being like bees around honey (me).
All this will give you a cool edge to yourself. This alone will raise your confidence because you will know girls are noticing you more.
Now you have to realize that you are unique. There's no one like you. The best thing I can tell you is that when you talk to girls you should not think about their hotness after you have notice them. Think this: She is the most beautiful girl in the world but she tells you she likes to kill kitties, eat shit and fart for fun. If you still like her you are weird, jajaja.
Have this mentality. Go and talk to her because you like her but focus on her mind. Your mission is to discover how is her personality and this is attractive as she will see you are not only interested in how she looks. This will relax you of the fact that you are talking to an attractive girl. Focus on her and don't talk to much about yourself. People want to be listened to.
The best example I can give you to know how to talk to a girl is to imagine any time that you were with someone you knew and you were connecting on any topic. You were happy, changing ideas, then he keeps talking and talking about the same stuff, and you get bored. You will make him know this because you won't contribute like before, your attention drifts, your body language, etc. You should talk to girls like this. The hard thing is to get to a point with girls you cold approach to want to keep talking to you, and then, keep the conversation going. Practice my friend, practice.
I want to end answering your most important question:
And how do you get that extreme confidence?
I never had this issue, but what you should do is fake it till you make it. Every time you go out think of yourself as an actor. Your role is the on of the most incredible seducer in the world. Visualizing you are good in something helps. Yes thinks this and at least you will reflect that vibe.
Eventually, with each success you have (any type of success in your way to becoming good with women: talking to lots of girls, brushing her hair early in the interaction while she is completely comfortable, kiss closes, same night sex, etc), you will be getting closer to become that character.
Hope this helps. It's a lot.
Cheers!