I think the key to writing good science fiction lies in understanding the different types that are already out there, and then finding interesting ways to marry the content together. Generally there are two different kinds, Conceptual and Philosophical.
Many of us already know this but maybe aren't aware of the dichotomy between the two. The easiest way to tell the difference would be looking at something like Star Trek and Star Wars. Though they are nomitively similar, their approaches are rather distinct.
I consider myself a Star Wars fan, but until the re-releases came out in the mid-90s I had spent considerable time in the Star Trek universe watching mostly the original theatrical films from both Shatner and Stewart Era Enterprises. What I found interesting was that I immediately latched onto the Star Wars universe when it initially came out, because who doesn't like lightsabers and hyperdrives? However it never possessed the emotional and creative depth of Star Trek. This is because Star Wars is Conceptual Science Fiction.
Conceptual SciFi aims to create an interactive universe. It gives us diverse worlds, technology, sentient species, language groups, and puts the reader into a concept induced coma. While this is good for creating a rapidly growing following in readership it has no staying power, that is unless the plot advances quickly to hold the interest. It's the orange chicken of reading, which you can consume rapidly in quick succession, but you lose appetite quickly. Character development takes a curbside for immersion, and the result is that the reader has no foothold in the characters that live in the universe.
Star Trek is another animal however. In this style of SciFi we find the opposite to be true, where character development is in ready supply and each of them have a warmth and depth that the reader can relate to and understand. There is a sense of moral weight on the actions of the characters that is otherwise absent in the concept centered SciFi worlds. This is because it is Philosophical in nature. Philosophical science fiction will play down the gadgetry of the world, emphasizing the consequences of technology, usually from an ethical perspective. For instance, though Data is an android, he reflects humanity in his programming, therefore it questions what makes a human really human.
As I mentioned before, it is important to find a way to marry these two together to make good SciFi, otherwise you have an overly shallow universe if all you focus on is technology and concepts, or an overly dry and unimpressive narrative due to the lack of immersion and philosophical waxing. The best advice I can give to make your SciFi better is to take conceptual elements and infuse in them philosophical meaning. If you have ever seen Bladerunner you will understand what I mean. Because it's not enough to have a language group or a type of technology that is there for the sake of being there. However, if the language can only be spoken through tonal sounds or if the technology changes the user over time to make them consistently less and less human, your start making your narrative not only conceptually interesting, but also with depth. It will be provocative and fascinating to confront and grapple with.
If you start here, I am certain your SciFi will really jump off the page.