I've been exploring passive income ideas for a while now, and I think some of the best options to start with are creating and selling online courses, affiliate marketing, or investing in dividend-paying stocks. These options require relatively low investment and can be sustainable in the long run. Online options like creating and selling ebooks or starting a blog can also generate passive income, and they're pretty easy to get started with. Offline options like renting out a spare room on Airbnb or investing in real estate can also work well, but they often require more upfront investment. In terms of time and effort, it really depends on the idea you choose, but most online options can be started with just a few hours of work per week.