Make every word in your story count. Adding words just to increase your word count will sound just like you did that.
If you can rewrite the sentence without the superfluous words, do it. Make your point clearly and quickly.
Use your story to tell the backstory – don’t use backstory as a chapter or even a prologue. Intersperse a flashback here or there instead of narrating what happened to that point. And while you may have backstory that you used to create your character, if it is not pertinent to the story you are telling, then it doesn’t need to be said.
I always say you should build your characters by knowing their history to help make them seem real and consistent. It is enough that you know that, for example, Sheila lost her favorite doll as a child, but unless that doll is somehow instrumental to the plot, such as it turns up buried with a skeleton, then it doesn’t have to be a part of the story.
Keep your sentences simple and dialogue natural (the way the character would realistically sound). Trim your redundant phrases and avoid using lengthy and difficult words when something simpler and easier to understand would have sufficed. Say “sit” instead of “sit down”, or “he thinks” instead of “he thinks to himself”.
Remember to show and not tell. Instead of wasting words telling readers that she was happy to see her long-lost husband, have her run into his arms, smile, or squeal with delight. Don’t qualify descriptions with unnecessary adverbs – have your character yell, not talk loudly, or whisper instead of talk quietly.
Would you start every statement with the name of the person you are addressing? No, and neither would your character. If you have an ongoing dialogue between two people, there is no need for each character to continually address each other by their full names. There is also no need to write “he said” (proper name or pronoun) with each sentence.
Instead of writing “She spoke to him while she folded the laundry”, try instead to describe the action outside of the dialogue: “She carefully folded the shirt before putting it into his drawer. (next paragraph) She said,…”
Use strong verbs to show what your character is doing ad don’t distract with added words. Say “She drove” instead of “She was driving” or “He fell” instead of “He was falling”. Also use strong words and phrases to express emotions, come right out and say “He hates her” and not “He was feeling hate towards her”. Say “he began” and not “he was beginning”.
Just like you don’t need to mention items or descriptions unless they play a role in the story, you should not have your characters engage in idle conversation just to pass the time. Everything you write needs to have meaning to the story. This applies to everything, not just dialogue. Don’t waste time describing the flocking of the wallpaper or the birds flying in the sky unless it is somehow significant to the storyline.
Keep the correct order of subject-verb-object to make your statements stronger. Use “he hit the ball” instead of “the ball was hit by him”.
Re-read your writing to find often used phrases such as that, etc, like, really, or now. Try reading the sentences without those words, if the sentence sounds right without the overused words, cut them out.
Writing exercise: Free write about any subject for 20-minutes. When you are done, get a word count. Now cut out any unnecessary words, trim the fat, make it stronger and tighter. How many words were you able to edit out?
Writing prompt: Take a quick look around your surroundings. Don't look again and write the first ten words that come to mind about the place you are in.

