hey, thank you for your this comment. Regarding the point that based on your experience passive income means constant work: Yes, I agree with you, passive income is constant work, my target will be to reduce this constant work to a minimum (e.g. a maximum of 2-4 hours per week) and optimize the revenue with the least work. I'm curious whether there are good strategies for doing that otherwise this will just be an empirical experiment :)
My approach thus far has been to not invest too much into a single idea before monetizing it, so I can "fail fast" without losing too much time.
It's a double-edged sword as I have people who paid for my DJ app and are expecting many new features. Which is good as it drives my efforts, but its bad because I can't spend that time working on new revenue-generating products.
The other approach I have when writing code is to try to have plans to sell each code module I write at least twice. For example the UI engine I wrote for my DJ app also powers my little iOS app released yesterday [http://itunes.apple.com/us/app/drinkpacer/id522224281?ls=1&#...], and I plan on using the audio engine for more audio projects. I call it the "combo effect".
