I can sum this chapter up in two words: “Character template.” Do a Google search (or Yahoo or Bing or any browser, I’m not advocating one above the other) for “character template.” You will find plenty out there. I personally like this one - http://www.eclectics.com/articles/character.html
Filling out a detailed profile makes writing much easier. Also, remember that you can always change these things later. Once you complete a character template, nothing is set in stone. You need that base though. You need that foundation on which you can build a complex person full of dreams and aspirations, emotions and feelings, ideology and philosophy. You need to know what each person looks like, where they come from, how they think about the world, etcetera. If you think all of this out ahead of time, then your characters will be full of life and purpose. They will be vivid and their emotions and aspirations will resonate with the reader.
I didn’t do these for the minor characters, but I did for the major characters. I think that doing these is absolutely essential. As a reader, if I don’t know where a character comes from and who they are as a person, then I have a hard time caring about them and what happens to them. For example, when extras die off in a movie, do you care? Are all lives equal? The answer, whether it should be or not, is “no.” Your reader will be deeply emotionally invested in the main characters and only cursorily invested in the tangential ones. Do everything that you can to build that emotional dependence.
