Decide how many characters are necessary for your story to develop the way you want it to, keeping in mind that the fewer characters you use, the easier the job of developing the story properly.
Therefore, identify your MAIN character and his/her role & your SUB CHARACTER/S and his/her/their roles.
Characterisation is also important. This includes:
- the appearance (the way the character looks),
- personality (the way the character thinks or feels)
- and behaviour (the way the character acts or feels) of the characters.