Everyone who is good is at least partially self-taught, even if they've been in a daily coaching program for the last fifteen years. You always have to bring yourself as the student to the lesson, and you always have to figure out, of all the advice and examples and possible choices out there, which ones make sense to you, which things you can cart away from the experience and apply, and which ones of the things you do apply, you want to keep.
(Search for discussions of counter in high level skiing around here if you want an example of divergent opinions, mirroring an actual substantial diversity of technique on that front from high level World Cup skiers.)
That said, how fast do you want to improve and how good do you want to get? Lots of skiers are very happy with how they ski now, whether they're carving or skidding (and whether they think they're carving but actually are skidding.) A few of the rest of us want to get MUCH better, MUCH faster than most people have reason to expect. The best way to do that is to get some help to identify your bad habits, to discover the limitations holding you back, and to try some of the variety of technical improvements out there to see what helps you. If you already knew, yourself, what was holding you back and how to get beyond it, it probably wouldn't still be holding you back, no?
I got into racing as a grown up, and my best learning has been from analyzing still pictures of me in the course compared with the top guys at the same turn. (The timer doesn't lie, and the still frame typically exposes the technical flaws behind that ugly numeric truth...) But how to get more like those fast guys is also helped by getting individual coaching. And you've got to be willing to listen, to try, and to experience the discomfort of pushing yourself out of your comfort zone in an effort to expand it.
There are 60 year old racers in daily masters programs who just practice the same sub-optimal technique rut, over and over. And there are skiers who are not in lessons who can experience a breakthrough. But your chances of improving more rapidly increase if you get some outside help from someone good.
Me, I've probably got to improve my times this year by a full second just to avoid getting passed up by my teenaged son, so--subject to snow availability--there's definitely a Thanksgiving one-week racing camp in Colorado in my Fall future and some Masters drop in training through the rest of the year.*
*Though the writing may be on the wall on this one anyway. My son is much bigger and stronger every year--especially this year--and in one year he went from getting beat by my brother by three seconds to beating my brother by four seconds. Given that last season in one race he was only four tenths of a second slower than dad, my time may be up. On the other hand, I still have, er, substantial room for technical improvement, so we'll see.