We have all been guilty of this when we first start out and it's maybe the number one sign of an inexperienced author. Point of view is one of the toughest things to master. The only time you are allowed to jump into several heads is when you write in omniscient point of view, but it often leads to confusion for the reader. It's also not a style that is commonly used in modern literature.

The reasons why beginners fall into this trap is because they haven't mastered the art of showing multiple characters' actions through the eyes of the protagonist. Telling the readers about someone else's thoughts and feelings is just too tempting and authors often think that readers won't understand the state of mind of the other characters if they don't catch a glimpse inside their heads. Guess what – they don't need to. Not knowing what another character thinks or feels is part of the suspense and trying to figure them out. Besides, a lot can be accomplished by body language and behavior.

Example:

"I don't know, TG." Zena's smile is crooked. His plan is bound to backfire.

TG stares at her with annoyance. As usual, she just doesn't get the big picture.

In the second sentence, I jumped from the narrator into TG's head by telling the reader that he thinks about Zena. If I keep jumping back and forth, it will be exhausting to the reader and likely make their head spin.

A lot can be inferred by body language alone. Let's go back to the scene above:

"I don't know, TG." Zena's smile is crooked. His plan is bound to backfire.

"Yeah, whatever." TG rolls his eyes in his typical, patronizing way – obviously not grasping what her problem is. Why does he always have to take those huge risks?

In this example, the reader can infer his annoyance by his response and eye roll. It also tells them a lot about their relationship. While Zena is prudent, she also tries to avoid conflict by giving him a vague statement instead of coming right out and telling him that this is a bad idea. He is a risk taker with little patience. All this could be said by staying in her head. We don't need to know what he thinks of her to get the full picture in this scene.

So as a newbie, pay especial attention to head hopping. Only change narrators at the beginning of a new chapter or after a clear section division. You also don't need to tell a reader who the narrator is - that should be clear if you have distinct voices and personalities. If all your characters sound the same, you need to evaluate their character traits to make them unique. That takes practice, but if you have them clearly defined, it's not as difficult as it might seem.