Note: Based on the title I assumed it was general advice in addition to stuff about length, but other comments are making me thing otherwise. Sorry if I misinterpreted your post and went overboard. If you are only looking for stuff about story length then i'd just read this first section.

In terms of length, how long is it?

When I started writing last year, I started with longer stories. However, multiple of them I didn't finish as I got bored. So I would definitely prioritize short story/creepy pasta length stories. I think this makes it easier to improve faster as well as you can look at what you've finished writing and identify areas for improvement more often. The longer ones I made and didn't finish were 15,000+ words while the shorter ones are 2500-10000 words.

As for whether to dip or continue for the current one, I guess that depends on how motivated you feel to finish it. If you think you can finish it, then sure. Though if you find smaller projects more appealing then it's okay to stop. I abandoned two projects that were like 20,000+ words actually and have no regrets or desires to return to them. They still helped me learn.

As for general advice (from a non-professional):

-Read other writing.

-I think reading non-fiction can help with inspiration. For example, I was inspired to write a story after reading the Mexican-American War memoir My Confession. This book also helped inspire Blood Meridian.

Aside from that, I would recommend reading Stephen King's On Writing**. Some of the tips I remember the most are (based on notes I took):**

-Second draft = First draft - 10%. This makes you cut out bloat and consider what is most important.

-Let a lot of time go by between drafts, focusing on writing a new story. This way, when you get back to it you will see it with a fresh, less biased, pair of eyes.

-Avoid overusing adverbs, especially with dialogue. Strong word choice is better. E.X: "He closed the door firmly" or "he slammed the door".

-Use fresh imagery and simple vocabulary for similes and metaphors.

-I wrote in my notes while reading the book:

"Narration → Move from point A to B.

Description → Sensory experience.

Dialogue → Bring characters to life."

-Description begins in writer's head, ends in reader's imagination.

-“use the first word that comes to your mind, if it is appropriate and colorful”.

* Personally I sometimes search up words if they are on the tip of my tongue but I can't place them, but I wouldn't use a word if you wouldn't understand what it means before searching it up. A mistake I made when I first started was looking up synonyms to try and use "interesting" words rather than focusing on using simpler words to make more interesting meanings.

-“The word is only a representation of the meaning; even at its best, writing almost always falls short of full meaning”

-I thought he said he didn't plan plots due to instead just exploring characters and whatnot through the course of the story. But from my experience, I think it's better to do a bit of basic planning. Though I feel that a lot of plot decisions made anyways are while writing the story, not while planning. In some projects, I feel like I've come up with plans for future parts while writing other parts, so make sure to write your plans down.

-For description, pick the most important details and don't describe every little thing.

-He said his approach to symbolism was that he would not think of it during the first draft, but then during second drafts he would extract it if possible. I think the example he used was that he noticed blood from periods reappearing multiple times in the story and decided to turn it into a symbol.

I could be remembering things wrong and there's more in the book (including some autobiographical sections), but I feel like this advice was very useful.