It's relatively easy to create a simple 2D character, but much harder to bring it to life. Without a sense of personality, your character is just an image on a page, but by thinking about its 'motivation' - how it behaves and moves, its facial expressions, what it does, its sense of style, what it likes/ dislikes and the environment in which it lives - you can make the character you create much more believable.
It's all about the planning. From the very start of the character creation process you need to think about the clothes, objects and props that could be used to bring your character to life. This will help you transform your flat pencil drawing into an image that really jumps out from the page.