My generalizations are no doubt particular to my own psychology and my own hang-ups, but so goes it. To begin with, there are a few things I can briefly and positively identify as necessary to move to the 'A' list. They are:
The turning point, for me, was my first game with Taliesin.
The game itself isn't inordinately interesting or skilful (on either of our parts; I ambushed Taliesin when he had barely stepped in the door on his return), but I learned more from that game than from my previous 200. The combination of Taliesin's steep reputation, plus his amicability and willingness to discuss tactics with me, plus the gaping quantities of free time I had then, led me to spend about a half hour considering *every* move of the game, even the ones that seemed obvious. This was critical.
My focus allowed me to beat a superior strategist, but more importantly, it brought everything I had learned about the game out of the seclusion of my memory and into a dynamic contemplative arena where observations and comments, rules and generalizations, weaves and reactivities all collided again and again. (In my head, still, not in the actual battle.) The existence of a battle that I was actively interested in kept this contemplation continuously anchored to real situations, which can be harder to do in purely abstract analyses. Anyway, the result was not so much that certain observations or rules triumphed over others, but that they all got to know each other; in other words, the relationships among them all became much clearer to me. Or think of it as miniaturization technology: all of this information which I already possessed was compacted down into a form which was not only more compact, but also more precisely delineated, and easier to use.
Afterwards, I continued to have unusually good focus. I played Taliesin another eight or nine times, mostly with similar determination, and I also concentrated unusually hard on my d-1337 initiation battles, all against moderately strong players. As a result of all this concentrated effort, I became wise.
So compared with two months ago, it's not really that I have any more knowledge or experience about how the game works, but my understanding of it is much more native. (Although I did pester Taliesin for his takes on some basic knowledge, which was also helpful.) A laundry list of some base knowledge that is nonetheless quite important:
Beginning with my second game ever, I've made extensive matrixes whenever I felt it might be helpful. Yaron used to do this as well. I haven't done it in a while, but I think it was very useful for picking up some good navigational techniques faster than would have otherwise been the case. Basically, you just do out every possible outcome of a situation. You can either do them synchronically, looking at a single turn (great when you are exploring how to react to SPFPSD with complex setups), or diachronically, looking at a tree of possible spellflows 2 or 3 turns into the future. I found the latter to be especially useful.
I can't stress this part enough. The first Slartucker, the focused one, has lost maybe 10 games at the most, and these all to top players (and players who play like top players when they are in top form). 10 out of 144 losses! The second Slartucker doesn't ever beat top players unless they screw up badly (and doesn't deserve to).
[As of November, I've gotten more consistent about staying focused, and my ELO has shot up about 80 points. Not a coincidence.]
-- Slartucker