Ask yourself what each character likes and dislikes. Lists the character's strengths and weaknesses. Make sure the character is rounded and has both good and bad qualities, just like a person in real life. For example, while your main character may serve as the world's hero, he has to have weaknesses and everyday struggles. Otherwise, your readers won't buy into the character.
Develop a distinct voice for each character. Every character must have his own voice. Voice means the character's diction.
Write from one point of view per chapter. Handling multiple points of view in one story is difficult enough, but attempting to mix and match them in one chapter is even more difficult. It's often jarring to the reader to suddenly jump from one point of view to another within the same chapter, so try to stick with one point of view per chapter.
Grow your characters. As your book evolves, so too should your characters. Make sure your characters progress logically and realistically. For example, if a character is mainly pessimistic and struggles with drugs, it's unrealistic for him to change to a drug-free and positive lifestyle in one chapter.
Focus on the story. Readers expect to follow a story. Your characters may be your strong suit, but they must remain secondary. Writing a multiple point of view tends to make the writer invest too much time and focus too heavily on each character, which takes away from the story.
Write each point of view regularly. You don't have to switch back and forth between each character every other chapter, but you do need to keep every character involved in the story. Mary Kole of the Andrea Brown Literary Agency says that keeping each point-of-view character evenly spaced allows readers to remember the characters.