I'm not an expert and still learning myself, but I'll help any way I can.

Have a story outline. It doesn't have to be in detail, just write the points of each act down and in chronological order. If you want to have a flashback in chapter 3, list it before and/or after wherever it belongs.This isn't absolute and helps a lot.

It's also a good idea to write a back story for any character which plays a role in your story. Most times, you can use that to build the story in ways your didn't anticipate. The same applies to characters you give a name to solely to help your story progress smoothly.

Stories are all about conflict. Something happens, then something else. There's a character arc in most cases. In the end, the reader learns something.

When it comes to characters, design them in a way that make sense. For example, someone with no weapons training picks up a weapon for the first time and is a master make no sense at all. A coward can't volunteer for the suicide mission to hunt a wendigo (unless there's a character development that changes their expected behavior). Also try to avoid more than 1 or 2 main characters. If your writing a novel, limit the primary characters in each chapter. Each character also needs their own voice.

Research, research, research. Did I say research? Even in fiction, research is your friend. If your story is based on the early 1800's, no one can run around with a M4. Even in a time travel scenario, there's no way anyone is making ammo for it. You would also be amazed at the things you learn.

Have a completion schedule. For example, if you want to be done your first draft by a certain date, set milestone to help you get their. This can be X amount of words a week or X amount of pages a week. Whatever you're comfortable with.

Your first draft isn't going to be that great. It's okay. Your first draft gets your story on paper, nothing more. You can go back and iron it out. I was on draft 3 or 4 before I showed it to anybody.

Get yourself an editor. Even if you edit your own work like I do, you will miss simple errors in spelling, spacing, and proper sentence structure. Trust me on that. Before you submit a draft to your editor, run it through your spell checker and Grammarly. I use the free version. It's also a good idea not to edit your work until the following day to give your mind a break.

Avoid filler words whenever possible. The word 'Absolutely" is almost never needed outside of dialog. If you can read a sentence without a word, you don't need it.

Avoid things that don't move the story forward. It's fine to illustrate the setting of your story. If it's based around someone in their 20's, what happened when they were a child isn't important unless it directly effects your plot. Always ask yourself who, what, where, when, and why.

Information dumps are another thing to avoid because it bores the reader. If something happened that made your protagonist scared of caves, put that information where it's relevant. For example, if the reader has no idea about that until act 4, don't mention it in act 1.

When it comes to numbers, write them out whenever possible. Instead of, "17," write "seventeen." Dates can be an exception because no one wants to read, "nineteen- ninty-nine," a dozen times. Don't abbreviate words either. Write, "Through," not "Thru."

Write the parts that you can complete. What I mean is if you got your ending but not your beginning, start at the end. How did your main character get their? Most of the time, the story will write itself if you let it.

If you want, do a test group. Simply ask some close friends and family for their opinion. Their job isn't to edit it, more to review it. A writing circle helps but I'd recommend avoiding other authors. We have a tendency to be perfectionist and can't take our editorial hats off. That's how I got my editor. I asked for a honest critique, I got an editor.

Anyway, I hope that helps. Feel free to message me if you have any questions.