I have removed the previous posts. The most valuable lessons from tango may only be learned through dancing, not by reading abstract concepts from a blog. On the contrary, if you have an abstract concept about some aspect of tango before you dance, it may actually prevent you from learning. So those texts were not helpful.
Here in Buenos Aires, I have put lot of effort on practice. I have found some of the ideas in the following articles helpful in my practice. Still, I don’t necessary agree with everything they say, nor is my aim to become “elite achiever” in tango.
If You’re Busy, You’re Doing Something Wrong: The Surprisingly Relaxed Lives of Elite Achievers
The basic idea in this article is that less is more. Elite violin players do not practice more than mediocre violite players. They just make more out of the practice.
Advice on Getting Better from an Accomplished Piano Player
According to this article, some people become addicted to flow, and value it as the end goal of the activity. But if you want to improve, you need deliberate practice, on your weaker points, which will break the flow. Just dancing under flow may improve your strong points, but not push the envelope by improving your weak points. Additionally, to master something, you need to practice on something that is more difficult than the one you want to mater. I also found very interesting the comment that during performance, great piano have a very clear idea, feeling, image, sensation about the piece they are performing, and try to go towards this, instead of just reacting to their own mistakes.
The Grandmaster in the Corner Office: What the Study of Chess Experts Teaches Us about Building a Remarkable Life
This article describes good practice in more detail, as well as what good teachers tend to do.
Cerebrar 
“Additionally, to master something, you need to practice on something that is more difficult than the one you want to mater. I also found very interesting the comment that during performance, great piano have a very clear idea, feeling, image, sensation about the piece they are performing, and try to go towards this, instead of just reacting to their own mistakes.
That could be highly relevent to performance dancing e.g. show tango. Social tango dancing is of course something else entirely.
Thanks Chris, for your comment.
My initial reaction was the same as yours, as can be seen from my comment on that blog entry. Social dancing is improvised, and having a perfect idea that you towards seems contrary to improvisation.
However, while practicing with my teacher last week I had an flash of understanding that expands on the idea. I believe it is applicable, but not for the duration of the whole dance, but for individual moments.
At moments, I can sometimes sense with my body, or even feel with my emotions, that something is not right, for example with the embrace. I can then figure out using my mind what it could be, from my image of “perfect” embrace, and then do the necessary adjustments.
The alternative, which to me seems inferior, is that teacher tells me to adjust my shoulders in certain way, and I just obey her instructions blindly. Her comment maybe right, but it is situational, relative to my current embrace. If I stop practicing with her, but still keep applying her instructions, I will probably end up exaggerating the “fix”, and thus create a new habit which is wrong in the opposite way from the old habit.
So If I want to be a good dancer, I need to create a mental image, sense and feeling of the perfect embrace, and constantly aim towards that.