The first questions here are:
- Between how many viewpoints do you switch?
- How many changes in point of view are there?
- For how long do you switch?
- What is the purpose of the switch?
The last question is the most important, because you can tell the exact same story without switches, from only one point of view.
In her answer, Lauren Ipsum assumes that you are narrating the lives of an ensemble cast, where each character is equally important and has roughly the same time in the "center of the stage". Dale Emery assumes that you are switching between one central and several minor characters. But there are other possibilities:
- You might tell a love story from the perspective of two protagonists that are easily distinguishable by their individual voices and concerns and easily identifiable because there are only two options.
- You might only switch once. For example, many crime novels start with a prologue from the perspective of the criminal or the first victim, and the rest of the novel is told from the perspective of the sleuth.
- You might change the point of view only for a short paragraph or sentence, as Stephen King does.
- and so on
Each of these and the many other "rhythms of switching" must be handled differently, and how you handle them will be dictated by the purpose of the switch:
- Do you want to show contrasting views of the same events, as in a two-viewpoint love story or legal drama (e.g. the movie Rashomon)?
- Do you want to create mystery and leave the reader wondering who it is that we see acting, as in a detective novel when we see the murderer doing things before we can identify him?
- Do you tell the tale of a whole world over many generations?
There are as many ways to handle viewpoints and viewpoint transitions as there are novels. There is no recipe for this, rather it is an artistic decision that you must make according to your artistic vision.
One of the most famous multi-perspective novels is probably William Faulkner's The Sound and the Fury. Each of the four chapers is told from the viewpoint of a different person, but the chapter headings and first sentences do not tell us who the viewpoint belongs to. It takes the reader a while until he realizes the identity of the protagonist (in fact many of my class mates needed the teacher to tell them). This is not a shortcoming of this novel, but obviously the author's intention. I don't want to speculate on the purpose, others have done so and you may read up on their arguments, but it is clear that you don't have to label your sections, if you feel that your novel works better without them.
One preliminary choice you'll have to make in this context is if you want to change viewpoint at all.
Personally I find that viewpoint changes tend to throw me out of the story. I have gotten into the character, am interested in his or her fate, and now I have to make an emotional and cognitive effort to get into the next person. And then back to the first person in the next chapter. And back and forth, all through the book. Which is why I seriously dislike action novels told from mulitple viewpoints.
When I read George R. R. Martin's A Song of Ice and Fire, I found that I began to skip over the chapters with different viewpoints to the next chapter told from the same characters's perspective. And near the end of the series I stopped reading those character's chapters that I disliked or found uninteresting.
The viewpoint switches work in Faulner because there are only four chapters and those chapters are long enough to be read as complete tales unto themselves.
I am sure there are many people who love getting into many people's heads, but I am equally sure that I am not the only person who dislikes this. During my writing I have found that I sometimes want to switch viewpoints because it makes my telling of the tale easier. It is often not a choice that promotes my vision, but a choice based on laziness and a lack of ability.
Make sure, before you think about how to switch, that you really need the switch to tell your story at all.