Pick your overall point of view. Is the story in third person or first person? If it's in the third person, is it the third-person objective (meaning you record only actions and speech, not thoughts) or third-person omniscient (meaning the narrator knows everything, even the thoughts of the characters)? Identify the point of view you want to use to tell your multiple perspectives and stick with it throughout the story.
Choose which characters you will work with. Going into the head of every character in the story might be difficult, so decide what specific characters you will focus on and stick to them throughout the story. Avoid jumping into the heads of very minor characters unless there is a very good reason to do so.
Decide whose point of view you need for each scene. Whose perspective is the most important in the moment, and why? Move into another character's point of view when you want to highlight that character's specific thoughts or actions in that scene.
Clearly indicate you have moved into another character's perspective. If you want to change perspectives, give the reader some clear indication that you have done so. Jumping directly from one character's thoughts to another can be jarring to the reader if you do not offer some transition. The most direct way to switch characters is to use a page break or a "break" symbol in the text, indicating a new character. A more subtle way is to give the inner thoughts of a character after an objective description. For example, you could describe of a scene, place or character, and then give the new character's perspective. This way, you can ease the reader into the new character's perspective without the change being jarring.
Give each character equal weight in the story. If you are using multiple points of view, give each character equal time. If you find that one character is not given much time in the story, think about eliminating that character's point of view altogether.