There's one thing that all author's should not overlook. The importance of diversity in their characters. Whether we intend it or not, many people look up to or despise the characters in our books based on their qualities and realism, even when that realism is quite obviously embellished. One thing that all authors should consider is, does your story involve enough character diversity? Look at the world around you. While you may find one "type" of person or another within your social circles or even within the neighborhoods you live, look at the world around you at all times. When you're writing scenes and interactions with characters, even those in the background, should be meaningful in a way that displays the real world. This becomes even more important when you're writing novels intended for younger audiences. What better way to open minds than to portray the world as it really is, diverse. People of all cultures, faiths, race, religions, philosophies, etc, live together. Make sure you consider that the next time you add a new character in your novel. Perhaps adding one from a culture you're not familiar with, may even add the spice to your writing you were looking for!