How to Know When to Switch
Question: So I've noticed this question gets asked quite a lot, so you're probably just done with everyone asking. But when you change POV how should it be done? In my planning, I can't decide how or when. I just know that when it's mostly centered on my main character it'll be in the past while when it is focused on my MC and others it'll be present. Is there a certain list of Do's and Don'ts? How often is too much of changing that it hinders the flow of the plot? Sorry to repeat a question and thank you for your time.
I'm not sure from your question whether you are asking about changing POV characters or staying with the MC's point-of-view but switching from an event in the present to one in the past.
If you are switching to and from the MC's past, then you have to consider when the reader needs to know certain things about the MC's past in order to make sense of his/her behaviour or attitude in the present. There are different ways it can work.
You may show the present first, to create a mystery, and then switch to the past to solve the mystery. For instance, at the start of Casablanca
we see the main character Rick keeping everyone in his life at a distance and being upset when a woman he used to know walks into his bar. The audience wonders why. Then the film cuts to the past and reveals how he once had a love affair with this woman that ended when she broke his heart. That explains everything.
On the other hand, you could show an event from a character's past - perhaps a time when he was betrayed by his mentor. Then you might flip back to the present when he encounters the mentor once more who asks for the
character's trust and help with a certain problem. Knowing about the past helps the reader understand the emotions the main character is feeling in the present.
You have to judge for yourself what makes the most impact in your story.
What can disrupt the flow of the story is when you are frequently jumping back to the past and either ...
1) The story in the past is not interesting, because it has no dramatic structure to it.
2) The story in the past does not shed a necessary light on the events in the present.
In such cases, the reader can get impatient with the flashbacks interrupting the story.
If you are telling the story in chronological order, but switching POV characters, then you have to think in terms of cause and effect. If there's an event that matters because it is the cause of the next key plot event, but the main character cannot find out about it in any logical way (for instance, if he's not there to witness what happens) you may need to switch to the POV of another character who can observe the event.
Of course, this gets more complicated if you have several story lines running throughout the novel, told from different POVs. You may want to map out the sequence of events for each story line separately (to make sure it hangs together and is complete). I prefer writing each event on a separate index card. Then you have to play with arranging the cards/events in different orders until you find the flow of events that makes the best sense chronologically.
(This should be done before you start messing about with telling the story in a non-chronological way.)
The key is that each event should be a necessary part of a dramatic arc (either main plot, subplot, or some other throughline) that helps create meaning in the story.