Congratulations on finding the secret treasure. Not many have your perseverance--you are a great and patient reader.
I will list all the secrets I've learned of this art here, and I'll add any secrets you send me for others to find.
Start with your end in mind. I pretend that I am the reader of the piece--even before the piece is written. I note my reactions--do I feel sad? angry? do I want to do something? What thoughts do I walk away with? Then I work backwards from there--what writing will evoke these emotions?
Mean something. Whatever you say should be crisp, clear, and concise. Convey a meaning. Plant thoughts in your readers' minds.
Structure your work. I always work within a structure--mostly because my very first work, Marble Springs, had no structure whatsoever and took me 5 years to do. The thing kept growing! and growing! It was a giant beast devouring all of my thoughts and energy and time. And it is still open ended. So I decided to limit my creations to fit within a structure. Then I discovered that the structure becomes part of the meaning of the piece. Ferris Wheels, for example, is a circular argument--the narrator comes back to the beginnning. Disappearing Rain really is about an intricate structure of repetition and symbols, angular ideas fitting into the smoothness of waters and rivers, just as the angular brush strokes sketch in the meanings of water and river.
Make many readers happy. Readers have different abilities and different motivations. Electronic literature can be hard work! So I always work on multiple levels:
Be passionate. Dan Waber says "If I were to give any words of advice to artists considering working
in the digital domain I'd say pretty much the same thing I'd say to
any artist. If you're worried about what other people are thinking,
it's probably not very much fun for you, and the work will suffer as a
result. Find a direction that you are passionate about and you'll
forget that anyone else's opinion even matters. The way to find a
direction you're passionate about is to look at as much existing work
as you can. If you still can't find it, keep looking. The more you
look the better. Absorb influence, don't avoid it. At our best, we are
greater than the sum of our influences. So it behooves us to have as
many influences as possible so that the sum which we may exceed is as
vast as it can be.