A flashback is one of the literary techniques used by writers in narratives. It is the sudden interruption in the story in order to present an earlier scene, episode in the story, or a part in the character's younger lives which was not shown in the previous parts of the story. It is a very effective way in arousing the readers' imagination. In using flashbacks...
~Use present tenses to talk about in the events in the present story time and use past tenses to describe previous events in the flashback.
~Try not to start your story with a flashback. Start by showing(tv) or telling(book) the readers on how and why the flashback started in the the first place.
~Make use of a powerful situation or strong emotion to introduce your flashback.
~Try to make flashbacks answer missing pieces or information in the plot and characters.
~Lastly, in a written work, try to keep flashbacks short. Also make sure that the flashback has a beginning, middle,and ending. Then continue with the main storyline.