Give It Time...

One of the main differences I have found in making the transition from writing journalism to writing fiction is the importance of the 'slow cook' approach.
Knocking out a double page spread on deadline is a valuable skill, and one that ensures fear of the blank page will never be a problem.
But stepping away from copy is a luxury few reporters can afford. Putting a story on hold for a while, turning down the heat, walking away... all of these are unthinkable in a newsroom, just as 'knocking out' a short story should be unthinkable to the writer of fiction. It is the act of coming back to a piece of writing afresh that enables the polishing process to begin, and the time that has elapsed will give the necessary objectivity on your return.
Basil Bunting wrote seven key points for young poets on the back of a postcard, so often was he asked for advice. The final two points are pertinent here:

Put your poem away till you forget it, then:
6. Cut out every word you dare.
7. Do it again a week later, and again.

I have found this to be sound advice where writing poetry is concerned, but also more recently in my short story endeavours. I actually prefer to leave a poem for a good month. Striking out words comes more easily when you are returning to something with fresh eyes. And so it goes for short stories, although I tend to leave these for a couple of weeks or so.
The editing process can only begin in earnest when you have divorced your mind from the preoccupations of the first draft. In a sense, you are returning to a piece of writing (or a poem) with the editor's hat firmly on. Every story or feature in a newspaper will have been looked over by at least two other people. Writers should seek to establish a similar workflow. The views of a respected peer are of great value once the first draft is on paper. Join a writers' group or get networking to find the best people you possibly can to offer critiques. Always allow some time to elapse before returning to your writing, especially when working alone as you will more easily be able to adopt the editor's role. Some writers find editing their work very difficult. I have been surprised, as someone who used to check over other people's words on a daily basis, at how hard editing your own writing can be. Objectivity is key, and leaving well alone for a bit helps enormously. When you return to your work you will notice how phrases you were originally unsure about will leap off the page, clamouring to be changed. Little details you never noticed whilst you were wrapped up in writing the thing will also emerge, and mistakes will be easier to spot too.
You may find you need to extend dialogue or ramp up description in places, but with short stories generally less is more, and the editing process, as for poetry, should involve a large amount of paring down.
You may find you have to rework the beginning, or indeed the end. Feedback from a fellow writer is especially useful here.
Bunting also advised young poets to 'fear adjectives; they bleed nouns' and to 'jettison ornament gaily but keep shape'...again, because of the economy involved, these are sound observations where the writing of short stories and flash fiction is concerned.
So, whilst my mission remains to crack on with my short story writing and put the best ones forward for publication or as entries to competitions, I am aware that nothing should go off in a rush. Nothing, in fact, should go off before it is at least a month old. And for a former journalist, that's really quite something.