If I were writing I would begin by giving myself and those around me a good long discusion about where we have been in life, where we once stood as opposed to where we stand now, and where we are headed.
I would then use that as a guideline to begin the process of reading, research, interviewing, and seeking advice much needed advice from others who have put out written material not just on christianity and self
help, but any subject for that matter, before finally drawing up the first of many drafts for my book.
Topics in my research would include what subject matter authors tend to focus on most, what is generally left out, what people in general would and would not like to see, how have what they have read has helped thus far, as well as all of the why's, how's, and when's.
That would be my basic stradegy in contributing towards helping humanity.
I wish you good luck in your mission and properity in all of your endeavors.