What is the more efficient way of self-teaching, when the return is diminishing? Keep on trying? or study more basic stuffs?
I am currently teaching myself a few subjects, but I have noticed that the learning curves are quite tricky now and then. Sometimes, it gets steep at the beginning, then it gets quite sucky later on (especially when I am in lack of some background knowledge. usually, I have to either look it up or make my own assumptions). Some other times, I have a humble beginning, but then it goes like rocket (e.g. for mathematics, when I tried to understand it, instead of memorizing it).
More specifically, I am learning writing in science on coursera. I am quite satisfied by the general tips (e.g. one main idea in each paragraph, and I had not known that at all), but when it comes to how "abstract", "method", "result", etc. The tutor's suggestions sound quite alien to me (I have little experience in research); furthermore, I am also not making good progress. Therefore, I am not sure if it is normal for someone learning something completely new, or simply because my English is too lousy (even as a non-native English speaker; hence, I had better to switch to other basic English writing courses)
So what is the more efficient way of self-teaching, when the return is diminishing? Work harder as no pain no gain? or switch to more fundamental things? While I am looking for a scientific answer (backed-up by researches), I would also love any personal experience or insight as an answer.