The first rule of writing flashbacks is the same as most other literary rules: don't.
Of course, most experienced writers know there is always an exception, an example of some famous, popular, wealthy author who pulled off the perfect flashback (or whatever rule is today's flavor.)
Any writer that finds a tempting flashback would be wise to stop and consider if it could be cut, and if cutting would harm the story. That's the real first rule. And I've been trying to sort out the how and why of a good flashback; I don't have much so far.
I have a simple idea. The problem with flashbacks is that the forward momentum of the story stops for what is usually nothing more than information--an infodump, another word often led around by a "never". In that sense, a flashback is like pausing the story to take a trip down Telling Lane, all the way down to where it intersects with Backstory Road. Nobody wants to stand on that corner, right?
Now, I'm not saying flashbacks are back in style or anything, but I think the key to a successful one would be that it advances the story. It affects the story. It is part of the story.
Consider the story of Todd. One night, Todd witnessed a murder through a haze of alcohol and drugs. The scene was dark and the memories fragmented, but now someone is gunning for poor old Todd. So, predictably, while he eludes the mystery murderer, the story is punctuated with a series of flashbacks, each one revealing new clues, pushing Todd into action. As memories bubble to the surface and pieces come together, Todd is also driven along an internal arc--perhaps one involving a girl or his family. (I'm not trying to be original here. Can you tell?)
The point is that the flashbacks lead to action. Todd tracks people down. He asks questions. He digs for bodies. He draws inexorably closer to the murderer--someone who is closer than he ever imagined, or something like that. Right? (Spoiler alert: It was his mother all along.)
Given a technique like this and an otherwise skilled writer, sure--I think a flashback might work. I'm also sure there are better examples, but it illustrates my only positive thought regarding flashbacks.
What I'd really love is to find some examples of stories where a flashback worked very well.
I spent the last month or more working on a project that ate up seventy to over a hundred hours per week. It still came in a few weeks late, accompanied by much red-faced yelling from my boss.
There's a writing lesson in there, of course.
All the while, I had thoughts of how neglected my writing was, and how certain famous authors were known for waking up two hours early every day just to write. I worried from time to time about how my platform must be suffering--not that I have much of one anyway.
Yet, work became the habit. Prior to this project, I loved writing. I put in the hours on the job, but most of my spare time involved writing, talking about writing, thinking about writing, or reading (often about writing.) Then Friday night when told not to work this weekend, I found it hard to let go. My mind kept drifting back to work. And even without that, it took effort to jump back into the old conversations.
And what was worse, my meager readership stats had dwindled, inspiring thoughts of anger and never-again towards working impossible hours.
But the lesson? Writing, as with anything, is about momentum and habit. And the world around me provides a kind of friction, a constant wearing away at my momentum. Keep pushing forward no matter what it takes. Get up an hour early. Stay up late. Tell the boss no. Set limits, create patterns, form habits.
The best advice I've heard this week is to always have your work-in-progress open and visible, even if you're wasting time on Facebook or whatever. It's not a bad idea. (Of course, it helps to have a WIP first.)
The old adages of "just write" and "be engaged" prove true once again.
Writer of speculative fiction. Current work in progress is an untitled dark fantasy novella.