Comment by o11c

Good sci-fi must first of all be good writing. Read through the entire text of The Elements of Style [1] - the original, by Strunk only, is in the public domain now, and almost entirely still relevant; newer versions do flesh it out more so get one eventually. Remember that since grammar and style aren't really separate concepts, you can break the rules ... but you have a "strangeness budget" (my term) that is very important not to exceed. And for speculative fiction in general, it is very common to have to spend some of the budget on introducing new vocabulary and concepts. Remaining similar to widely-known works (when possible) is a major way to reduce the cost.

To get good, you also need to actually, you know, write. A story of a few thousand words isn't hard to write, whether you tend to fall into the trap of endless worldbuilding or whether you tend to fall into the trap of writing by the seat of your pants.

For the science, there's a lot of reference material in [2]. Remember that realism doesn't necessarily make a good story, but any deviations should be deliberate (e.g. space opera is a distinct subgenre). I do personally find sci-fi tends to be better than fantasy because authors are more likely to actually try to make something coherent. (90% of everything is still crap though, whether due to lack of trying or lack of competence).

All speculative fiction is political, but try to leave a good story even if every part of your personal politics is removed from the story. If you can't do this, it's not a good sci-fi story (let alone a good overall story), at most it's a good $yourpoliticalfaction propaganda story (for sci-fi, this is particularly common for military glorification, weird sex stuff, and a whole host of society-ordering utopias/dystopias). Regardless, never "surprise" the reader with your take - if you have an agenda, put it in the blurb, tags, and in the first chapter; if you don't, you have no one to blame but yourself when you get (correctly) review-bombed (often, even by people who agree with your politics, since we read to escape). If you construct a metaphor to attack a real-world target, make sure a 5-year-old can't poke a hole in it; don't make your villain gratuitously stupid. (Note that "courtly intrigue", although in-universe politics, often isn't politics by a real-world perspective, just character drama).

The best writing is timeless. This is sometimes difficult for writers of genre-defining works, because "Seinfeld" is Unfunny.

[1] https://www.gutenberg.org/ebooks/37134 [2] https://projectrho.com/public_html/rocket/