There's this notion going around in the community sometimes that holds that the best way to progress on one's rationality skills is to make lots and lots of theoretical study by yourself or to go off and "level up" a bunch on your own prior to getting involved in object-level projects or efforts.
I think that's false and in fact that it's not only false but it's almost the opposite of what needs to be done. In point of fact, much of the time I've seen people go off to meditate in the darkness for a year and "level up" a bunch, this has not only not helped much but in some cases has seemed to actually harm, as people have a tendency to go in strange and unsound directions when doing this sort of thing on their own without feedback.
Instead, I think that if you want to make progress on your rationality skills, the best way to do that is to get involved with object-level projects and use those as testing grounds for your practice. Not only will this help you test skills in a more realistic and practical setting, but it will also provide demonstrations that you can later refer to to show how things worked (or didn't), and it will quite possibly help you build a secret identity as well.
So, yeah. If you want to be an advanced rationalist, don't just theorize - go out there and do stuff.
Looking back, to the extent that I developed rationality skills, I learned almost all of them by Go Do Something combined with deliberate practice.
That doesn't mean you shouldn't do the reading, or have the discussions, but they need the context of Went And Started Doing Something to work.
I think pretty textbook. Looking at actions and details, not results. Constantly going over everything I'm doing, during and after doing it, picking apart every decision and action and mistake set to stupidly high standards, including writing all of it up where secrecy permitted.
I'm guessing that misses the details that would most be useful to you, so likely you should say more about what details you're curious about.