I'm a published author of several novels and numerous short stories. I've also been an active member of writers' groups for many years. During this time I've been asked to write some articles directed at beginning fiction writers. You can find two of them here.
The first rule most new authors hear is that the writer must show instead of tell. It's excellent advice. The article I wrote on this subject was published by Writer's Journal some years ago, and it is still relevant. To read my text on the subject, click here.
A personal peeve of mine in regard to writers' groups is that reviewers often incorrectly complain about use of passive voice, thereby confusing inexperienced writers. To address this issue, I wrote a brief tutorial on the subject. To read it, click here.