Proverbs are an excellent source of story ideas. Listen to how other people speak - both on TV and on the street. Does your story follow an arc of beginning, middle and end? Does enough happen in it? I have to watch that I don’t put too much dialogue in as I love writing it (and indeed reading it in other authors’ work). Do you know your characters well enough to write convincingly about them? Some authors do character biographies. I haven’t but I do like to know the chief trait (in Eileen’s case stubbornness, an uncanny ability to drop herself right in it). Pictures from magazines can be useful for starting you off with ideas for physical appearance - always use in general terms. You don’t want anyone recognizing themselves. Not everyone’s flattered to be included in book.
Read work out loud, particularly dialogue, to hear if it sounds right. If you trip over it, your readers will. Reading it silently on screen or on paper isn’t the same - you’ll just read it but hearing it will show up the faults.
Get a copy of Brewer’s Phrase and Fable. It’s fascinating and may well inspire several ideas.
You must have a good dictionary and thesaurus. Don’t rely on the computer’s spell checker. It doesn’t differentiate between there and their, for example, or at least mine doesn't! The grammar check doesn’t allow for character names and I’ve found it irritating to have my characters all underlined in red/green! I know they’re correctly spelled, thank you!
Do update your Writers’ and Artists’ Yearbook annually. Things do change quickly.
Read inside and outside your chosen genre. Not only is it a great joy, inspiration for your own tales can come from many sources. Something usually outside what you do may well strengthen your work or give you ideas you may not have come across if you’d stuck to just reading in a narrow category. You are also less likely to plagarize by reading as widely as possible - you can’t copy them all!