First a wikipedia definition in case not everyone uses the same term:
Flashback (narrative), in literature and dramatic media, an interjected scene that takes the narrative back in time from the current point
The Writers Digest has a great post about this issue in which they offer 3 tips:
Your flashback should follow a strong scene. (so the flashback should not be your FIRST scene, though lots of TV shows start that way, with a scene from the future that makes no sense, and then a black screen that says ’72 hours earlier’ or something like that)
Orient us at the start of the flashback in time and space (in other words, don’t just give a time reference for the flash back, also set the scene in terms of characters and where they are).
Use verb tense conventions to guide your reader in and out of the flashback (tricky, but it depends on what tense your ‘current’ timeline is written in and from what voice)
In case ‘past perfect’ is only known to you because you studied French in school, Hallie Ephron has written a useful table to use for tenses and flashbacks:
TENSE TO USE FOR FLASHBACKSIf the main story is written in…Write the flashback in…Present TensePast TenseHe runsHe ranPast TensePast Perfect TenseHe ranHe had run
In novel or other literary form, I personally believe the best flashback method is to alternate chapters/sections of the writing, so that (just for example) Chapter One is set in the present, and ends by leading us into a scene that links to the past. Then Chapter Two is all flashback, related to the concept/theme/actual events of the final scene in the previous chapter. And so on.
I also liked Dan Goodswen’s answer in the same Quora question where he says he writes flashbacks in a different voice, so no one is confused. Read Quote of Dan Goodswen’s answer to Writing: What are the best ways to write flashback scenes? on Quora
For example, my main story is often written in the first person. To borrow the opening line from the novel I’m currently writing; I’m carrying her in my arms when I feel the first blow. But if I wanted to make this a flashback, I might use the second person, to differentiate the voice between chapters, and help the reader understand that this isn’t part of the main story. A second person flashback might look like this; You’re carrying her in your arms when you feel the first blow. The same sentence, but given an immediate difference by the change from first to second person.
I’m going to apply most of this (the past-perfect stuff I still find confusing but I’m game to try) on my flashback scene in Principessa.
Let me know if you find this useful, and please, let me know if you have other ideas on this!