Yes, good point about not blatantly copying other people’s hard work. I should have said in my original post that I would NEVER do that. I have eight years’ of University education behind me which resulted in three degrees, including a Masters. If I learned one thing at college, it is that plagiarism is, as you say, SO not cool. Not the done thing. I plan to give full attribution to the originating author and paste a link to their website on my website so my subscribers can follow up the data with the source if they choose to.
3. Start as soon as possible. Building a livable passive-income stream takes a tremendously long time, largely because of declining interest rates since the late 1980s. Gone are the days of making a 5%-plus return on a short-term CD or savings account. Today, the best 12-month CD is at 2.5%, and the best money-market rate is about 1.85%, which is not bad, considering such rates were below 0.5% just a couple of years ago. Know that every $100 you save can generate at least $2.5 in passive income.

Skillshare is more of a social learning platform where you can teach real-world skills. The range of skills that you can teach is only limited by your imagination - from board game strategies, garment construction, cooking tutorials, travel hacking, and relationship tips. I even saw a course on how to build a grown man's wardrobe. Creating a class on Skillshare is free. For each student who enrolls, Skillshare takes a 30% fee (Similar to Udemy). You are also provided a unique teacher referral link that lowers the fee to 15% for students who enroll via your referral. Note that all online courses on Skillshare go through an approval process based on specific criteria.
For someone my age, I have an extremely low risk portfolio of mutual funds, foreign currency, and bonds. It’s made a bit more risky by my recent exposure to cryptocurrency, but that’s the only “high risk” activity going on here. Nothing exciting, but it pays some nice dividends and beats the hell out of keeping money in a savings account. This is a way for me to hedge against the risk I incur by angel investing in startups.
Courses are similar to guides but they’re easier to produce for some subjects, especially tech subjects. If you’ve got a computer, a decent microphone and some screen recording software, it’s pretty easy to create high quality courses. You can sell your course through your own site or you can use a marketplace like Udemy to do all the heavy lifting. 
Good suggestions. I have many of these. One word about the “app” idea. I had a great idea related to personal taxes that I tried to get off the ground with my accountant as a partner. I would say it’s difficult to do this unless you have a coder on your team. Hiring someone is not really viable financially unless the app is simple. When we finally got the quote for a coder to write what we wanted (and after doing lots of mock ups ourselves and getting a demo for investors) the estimate was about 750k just to really get started.

4. Calculate how much passive income you need. It's important to have a passive-income goal — otherwise, it's very easy to lose motivation. A good goal is to try to generate enough passive income to cover basic living expenses such as food, shelter, transportation, and clothing. If your annual expense number is $30,000, divide that figure by your expected rate of return to see how much capital you need to save. Unfortunately, you've got to then multiply the capital amount by 1.25 to 1.5 to account for taxes.

That strategy seems waaaayyyy less risky than actively picking stocks of supposedly “reliable” stocks that issue dividends, which could be cut at any time due to shifting industry trends and company performance. Dividend investing feels like an overly complex old-school way of investing that doesn’t have a very strong intellectual basis compared to index investing.

If you’ve ever thought to yourself, “I wish there was a product that did this,” then invent it! Create a product, medical or otherwise, and sell it as a company or get royalties for it. It’s not impossible to figure out, I have many friends who have taken a concept to market. Don’t overlook an invention as a fantastic means of attaining passive income.