Determine the qualities of your main character and what he or she will look like. The main character may be the narrator of the story, but he or she will always be the character through whom the reader sees the imagined world. The role of the main character is to provide valuable insight into the "hero" character, since their point of view is the focus of the story. Generally, though, the hero is the main character or the protagonist or a combination of both.
Create a protagonist to add to your cast of characters. The protagonist acts as the main driver to help the story achieve its goal. In many stories, the protagonist, hero and main character are one and the same, but this is not always the case. For example, if Character A is telling Character B a story that centers around Character C, it would be clear that Character A is the main character. In this example, Character C would actually be the protagonist, because he or she is the driving force for the plot. Typically the story is told from the protagonist's point of view, and the protagonist is the character that readers care the most about.
Develop an antagonist for your story. Commonly known as the bad guy or villain, the antagonist is working against the protagonist's end objective and represents a desire to undermine his or her chance of achieving it. The antagonist may try to stop the protagonist from doing something like preserving order in the face of chaos or enforcing good to overthrow evil. Alternatively the protagonist may try to stop the antagonist from completing a goal of his or her own that will have negative consequences.
Give names to your characters that are appropriate to the era in which they live. For example, New York Times best-selling author Suzanne Brockmann chooses the names of her characters based on which ones would have been popular during that time to ensure authenticity. This means that naming your historical heroine Bambi detracts from the credibility of your story if it takes place in the 1800s. You will also want to choose your characters' names to coincide with their economic status.