Good writing comes down to a few choices you make on every line. We learned these writing the one-line notes under each world.
Be specific. Name the exact thing and use a strong verb. "A creature walks" is vague. "A tripod walker makes the crossing once a season" gives the reader a picture.
Vary sentence length. Short sentences feel quick and firm. Longer sentences slow the reader down. Mixing them keeps text from feeling flat. Reading your writing out loud is the fastest way to hear problems.
Pick a point of view and keep it. "I", "we", "you" and "they" each create a different distance from the reader. This journal uses "we" throughout.
Keep dialogue natural. Real people interrupt themselves and leave sentences unfinished. Dialogue that is perfectly tidy often sounds fake.
Include tension. Something should be wanted, feared or missing, even in one line. In "The jellies drift toward it anyway", the word "anyway" adds the tension that makes it a story.
Try it: take a sentence you wrote today and replace its most general noun with a specific one.