In no particular order:

1 Don’t use a predictable title. If the theme for the competition is, say, ‘Bridges’, and you call your story ‘Bridges’, you can be pretty certain that lots of other entries will have the same one. Call your story something original. 

2. Don’t forget the word limit. It’s easy for the judges to check! Too long is annoying and unprofessional; too short feels arrogant.

3. Don’t rush the ending. A strong ending is a memorable burst of energy that stays with the reader. It doesn’t have to be a ‘twist’ or a shock, it just has to give either a feeling of completion or sometimes a sense of loss. Poor endings don’t offer this, are often rushed and send the clear message at this point I ran out of ideas, or time. Inexplicably violent or tragic endings are just as unsatisfying.

4. Narration unbroken by dialogue. A story without any dialogue has to work very hard indeed to help readers identify and care about characters. Even a tiny amount of direct speech makes a big difference. 

‘It does, doesn’t it?’

‘You bet.’

5. No accidental clichés allowed. Deliberate clichés for mockery purposes might work, but be careful; it can be difficult to spot the irony.

6. Embarrassingly revelatory subtext. Watch out for subtext. Sometimes stories seem to reveal ideas the writer was probably unaware of. Are all your male characters rakishly attractive? Do all your female characters nurse resentment and plot revenge? Do all the women need rescuing by strong male characters? Are all the men/women/young people/foreigners/builders/white collar workers (name your population group) in your story wrong’uns, or dim? Stereotypes creep in. All these things are up to you, if you’re doing them by choice. If it’s happening subconsciously you might be revealing more than you intended!

7. Unexpectedly offensive swearing. If you use the rudest words in a story it can make it more difficult for judges to choose it because a) swearing has to be very finely calibrated to have the right effect on every reader. What seems an off-hand, mild cuss to one person is a disgusting outrage to another, and a lazy form of characterisation to another still. Powerful, if you get it right; disastrously off-key if you get it wrong. The power of cursing comes and goes between the generations too. Some 1950s rude words would seem daft nowadays but others would get you reported to the police. 

b) Certain swearwords are picked up electronically online, and intercepted by family-friendly filters. In other words, it’s difficult for organisations to publish/publicise your story online, which is off-putting. 

Cuss with care. Know your reader.

8. Sex (see Swearing, above. The same principles apply.)

9. Starting in the wrong place. Many stories take a long run-up before we get to the main point. School-aged writers are inclined to start a story about A Day at the Zoo with, ‘I woke up that morning…’ and a few more paragraphs of breakfast and bus journey before ever reaching an animal. Their writing improves hugely as soon as they get the idea that they could by-pass breakfast and go straight to, ‘The lion stared at me and licked his teeth…’.

10. Empty-hearted coldness. If there isn’t any sign of emotion, your story will be flat. For example, if your character is confronted by someone carrying a weapon, we would expect them to feel something. You don’t need to say they are scared/terrified/excited, it works better if you show it in the way they act, feel, speak or think. (Preferably without using the word ‘heart’!)

11. Make sure you write a short story, not a book condensed into the word count or something that reads like an extract.

12. Anticlimax. Keep the punchline to the end or towards the end, or things will trail off…

13. Retrofitting a story to fit a different competition theme. If you have a story already and re-purpose it by awkwardly shoehorning in something to make it fit the title, it’s often easy to see the join. 

14. If something startling is going to come at the end, don’t forget to foreshadow it earlier on in the story. If someone’s going to be killed with the lead pipe in the conservatory, someone needs to mention the lead pipe early on.

15. And the reverse of this, which is if you refer to the lead pipe/Glock handgun/lost handkerchief/stray dog in a significant way early on, something has to happen with it later, or the readers all feel short changed and keep wondering where it is.

16. Make your characters memorable. Differentiate them. Make their names different. If they’re called Mike, Mitch and Mick, you’re making the reader work too hard. (This is surprisingly common.)

17. Unpronounceable names are annoying, even if we only have to read them in our heads. Unless it’s really essential for your character to be called Honzuezhan Xvextzwytlzch, please reconsider.

(With thanks to Patricia McBride for her contributions.)