Make use of grammatical transitions whenever you begin a story with a flashback. This is simple if you use the verb “to have.” For example: “The last time Harry ate lunch alone, he had been stuck in between flights at...”. The “he had been” suggests that the story is now going into a flashback. On the other hand, use emotional transitions as well if you shift the story to the past. This means that the character is suffering something that will take his/her flashback into the past. For instance, if your character sees a couple displaying affection in public this could trigger his/her own memory of an old romantic experience. Know the reason of the flashback and see where you can transition into it through a trigger to start the story.
Importance of flashbacks
They are helpful when starting a story as they answer questions about the plot and character of the entire story. Remember flashbacks offer intricate details about things and you can use it to tell the backdrop of particular chapters or scenes in the story. For example, a gigolo could have a flashback to his childhood that would tell where he came from, his upbringing or relationships with family members that would make his character stand out. You can use this in the beginning to explain how he became such a person now.
You can use flashbacks to force a twist in the plot. For instance, the identity of a robber can be told in a flashback to the present crime. This is a must in crime stories and can be used in other types of genres as well. Be sure to give clues during the process before you explain the plot twist.