Gene Wolfe, my favorite writer, said that the advice he gave people was to pick a short story they thought was perfect, and try to rewrite it word for word from memory.

Presumably the idea is that you run into the same challenges the original author did — how to get from one scene to the next, how to direct or misdirect the reader, etc. — and by solving those challenges you understand the mechanics of storytelling at a deeper level. Since you've got the "perfect" version of the story as a key, you aren't just guessing, and there is a right and wrong answer.

He also said that, to his knowledge, nobody had ever taken him up on this advice.

But, Wolfe was a fantastic writer, and an engineer, so I assume his approach would be a practical and useful one for anyone willing to put in the work.

I just spent about 30 minutes trying to find the source of the quote, but failed. /shrug