Here are some sites that provide resources to help you improve your flash fiction writing.

Fusilli Writing Resources   Articles include:

• • ‘Show’ don’t ‘tell’
  • Titles for flash
  • Writing plot twists in flash fiction
  • Micro fiction: Beginning, middle and end – a theory of micro fiction construction
  • Entering writing competitions – six top tips

Science Fiction & Fantasy Writers Association    10 Hands-On Tips For Writing Flash Fiction

• • Ten useful tips

The Guardian   Stories in your pocket: how to write flash fiction

• • Author David Gaffney experiences writing and selling flash

Writers.com  How to Write Flash Fiction Stories

• • Good collection of tips
  • Suggestions for submitting

Writers Edit  The Ultimate Guide To Flash Fiction (And How To Write Your Own

• • Handy list of flash fiction subgenres with examples
  • Tips with links to more  details