Haha I remember doing this back when I did my creative. This is what I basically did:
- Ensure that your character interactions do not feel contrived
- Make sure that every sentence you write contributes to the atmosphere and/or progression of the story. If it doesn't, its better to take it out and replace it with something useful.
- Don't change tense during the story (unless you're having a prolepsis or analepsis - I'll talk about this later)
- Consider a complex cyclical structure rather than linear progression (e.g. analepsis[flashback] or prolepsis[flashforward]). This can add complexity to your story which markers like.
- Keep number of characters as low as possible if it suits your story. (This is often a debated topic but I personally preferred fewer characters)
- Vary sentence structure - have some sentences long and some short. Don't have a continuous barrage or short sentences consecutively or long sentences consecutively.
- Ask yourself whether the description of your setting is immersive enough for the reader such that they can really imagine what the environment of the characters are like. This is pretty tough lol and it's hard to do it by yourself so I just gave it to my teacher and asked his opinion on it lol.
Hope that helped! They were just stuff that I did so there's no need for you to follow them strictly or anything - they're just a small guide
English is already a pretty subjective subject so there's no real clear cut way to critique your own work but hopefully the above can act as a few pointers.