As both a writer and a fan of science fiction, I've noticed a lot of the elements that generally make it better, and some that generally make it worse. While some of these aren't specific to science fiction, I tried to narrow these tips down to those relevant for science fiction writing.
1. Don't be afraid to create a world.
Anything you write, especially in the earliest drafts, is yours and yours only. Within those pages, you can do whatever you want and create whatever you want. It doesn't have to be Star Trek levels at first, just start with the relevant stuff. If you want to make the setting engaging for the reader, then describe the landscape, the people, the smells, the feeling you get when you take your first arrive, the sounds that surround you.
A sub-tip you can do is to vividly describe an engaging, active place you know, like a market or a street corner. Then with that as a reference, do the same with the world you want to create. In my opinion, one of the things that made Star Wars: A New Hope (1977) great was its sense of realness, as a sort of reimagining of the sci-fi era of Metropolis and Buck Rogers.
2. Push your imagination to its limits.
Does it sound like a trope? Yes. Is it still relevant? Absolutely. A mistake I commonly see with writers is that they are unwilling to flesh out their universe. As a result, their science fiction feels more like boring old fiction.
Of course, you can also swing in the direction of Kubrick's 2001: A Space Odyssey (1968) and let your imagination run past the limits of it being a coherent story (that's just my opinion). If you want to read some really mindblowing science fiction, look at some of the material from the late sixties. This was when authors had very few limits, and they were writing about everything from celestial energy to laser beings to shooting a rocket past time itself.
I think that although the influence of LSD is undoubtedly present, we can definitely gain inspiration from material like this.
3. Don't forget to make your characters interesting.
One of the many writing pitfalls in general is to great a great story, and then forget to make the characters more than just the plot's means to an end. Again, Valerian is a great example of this, but in the opposite way: critics hated the characters' lack of chemistry and overall forgettability.
However, I think we can look at an earlier Luc Besson flick for what to do right: The Fifth Element (1997). Every character in this movie, from Corbin Dallas to the horde of Mangalores, had some definable character traits. Corbin is disgruntled, somewhat self-centered but not enough to impede the plot, and smart with tactics, Cornelius is somewhat bumbling, scholarly and a bit quirky, LeeLoo is curious, also good with guns, and passionate about the death of her protectors.
While some of Besson's characters are more fleshed out than others, he avoided the trap of making a beautiful setting and an interesting story and then subjugating the characters to do nothing but forward the plot.
Am I a best-selling sci-fi author? God, I wish. I just really like the genre, and I'm trying to cultivate future work so that the world never runs out of good science fiction (if that's even possible in the first place).
