Read! The best way to become a better writer is to write, but reading comes in a very close second. The more you read, especially in a given genre, the better you will understand what works and doesn’t work in your own writing. There are hundreds of Star Wars novels spread among dozens of authors, all of whom have different writing styles. While trying to copy someone’s style is discouraged, you can learn a lot from the way other writers work and incorporate it into your own distinct style.
Writing should be something you enjoy. Your story and characters should be something you care about. Don’t view writing as a thing you have to suffer through; instead, it’s a chance to live vicariously through your stories, and to share those stories with others. If you don’t enjoy the process of writing, your readers likely won’t enjoy the reading.
Consistency is a HUGE part of quality writing. Whether it’s how you use adverbs and adjectives, maintaining a theme, tenses, or points of view, nothing throws a reader more than inconsistent writing. Even if you’re technically wrong, be wrong consistently.
Word counts don’t matter. Quantity does not always equal quality. Ignore the word count when writing your first draft. A good story can be short and a bad story can be long. Focus on the quality of your writing, and you’ll find word counts are easily achievable. Don’t go into a writing session with the goal of a certain number of words. Instead, focus on getting a section done. When you are happy with the story you have crafted, then enable the word count, and fill in (or erase!) as needed to meet the word count.
If you don’t love it, change it. You aren’t inscribing your story on a stone tablet - the “delete” and “backspace” keys should be your closest friends. Write through the tough parts, the parts where you struggle, and then go back and rewrite them if you don’t love them.
Learn when to stop. Sometimes a writer just gets too “wordy.” If you find yourself bumping into a word limit, you should consider going back through and removing things that don’t actively contribute to the story. Sometimes this process requires being ruthless with yourself.
Live in the Star Wars / Emperor’s Hammer world. When you’re writing fiction for the EH, it needs to fit into the larger Star Wars universe by definition. The Force exists. Faster-than-light (hyperspace) travel is commonplace. Blasters and shields and droids are all not just possible, but normal. Write with all of that in mind.
Remember, Star Wars is a space fantasy, not “hard” science fiction. Not everything has to be rooted strictly in scientific plausibility. If you can explain it plausibly, do so. If not, find a creative way to gloss over it - just don't go too far. Different rules apply to "hard" science fiction, but in a galaxy with the Force and lightsabers, you can fudge a little here and there.