I think it's just "drawing more and you'd become better" principle.

And it's about time as well. I tell you and it's totally true, I have difficulties in making great details as well, cuz my strokes are rush and rough (when you magnify my works, you would see there're many split ends, I still find it hard to control my strokes. That's why I have to minify my drawing, to cover the faults ), so I need to spend more time to repeat erasing and drawing till I get the best.

So, don't be frustrated, keep on going and your afford would finally pay off. I have many thing to improve as well, so let's keep going together.