I agree mostly with the real estate advice. I’m looking for ways to take advantage of the condo I own to get up the rent from ~$0.90/ft to the $1.2-1.5/ft that seems more like the range in the same area. I’d have to put in a bit of capital (probably 10k on the low end for just the basics up to 40k if I wanted to remodel the kitchen and 2 bathrooms up to par with the area), so the return is likely there if those upgrades warrant $1.30/ft (given the unit is larger than most 2br/2ba in the area).
If you have specialized knowledge in a certain topic, you can put together an online course to teach others. For example, if you have experience in real estate investing, you can create an online course “Real Estate Investing 101”. The benefit of an online course is that once you create the course material, you can sell it to as many people as you want.