Another option: Consider starting your own real estate investment group. This is a great way to team together with other small investors, either via pooling your money together or simply by learning from eachother. According to Joseph Hogue, CFA from, “The common bond in all real estate investing groups is that you help each other compete against the big money players to get the best returns.”
Instead of buying lots of individual bonds, you can buy a bond ETF to diversify among many bonds and leave the selection to the ETF managers. Bond ETFs come in many different varieties including government, corporate, short-term, long-term, junk, municipal, international and in variations and combinations of each type. Like most investments, higher yields mean higher risk. So choose your bond ETFs based on your risk tolerance, asset type, and liquidity.

That’s a nice read! I love your many tangible ways mentioned to make passive income unlike certain people trying to recruit others by mentioning network marketing and trying to get them to join up and sell products like Amway, Avon, Mary Kay, Cutco or 5Linx. People get sucked into wealth and profits and become influenced joiners from the use pressure tactics.
Unfortunately, I can’t answer that conclusively one way or the other. It all depends on you, what you like to do, your work ethic, personality, etc. If you are a good writer perhaps you could write a book and make money that way. Or, you could start your own website and do affiliate marketing. Just because you are young it doesn’t mean you can’t make money doing at least a few of these ideas. I wish you luck in your money making efforts!
After these tenants move out, I'm thinking of just keeping the rental empty with furniture. It sounds stupid to give up $4,200 a month, but I really hate dealing with the homeowner association, move-in/move-out rules, and maintenance issues. Given that the condo doesn't have a mortgage and I have to pay taxes on some of the rental income, I'm not giving up that much. The condo can be a place for my sister, parents, or in-laws to crash when they want to stay in SF for longer than a week or two.
The organizing principle behind this grouping, appropriate economic units, is relatively simple: if the activities are located in the same geographic area; if the activities have similarities in the types of business; or if the activities are somehow interdependent, for instance, if they have the same customers, employees or use a single set of books for accounting.

Viral marketing is a customer-focused approach, so the first step is to identify the target demographic for a product and what they value the most in products, requiring marketers to research and analyze demographic data. During the Blair Witch campaign, the filmmakers and main marketing agents for the movie were accomplished film students. They examined what made horror movies compelling for the demographic of teens to young adults they were targeting, as well as explored how that demographic shared information. They used this information to focus on their product's mystery, and they concentrated their early efforts on the Internet where they knew they would have the best chance of reaching a younger audience. (See also Youth Marketing)
When I started building my architecture-related business in 2008, I made my first dollar through advertising. I’d spent a lot of time and money building the site and getting traffic. Then one day I threw an ad on the site one day, and I made $1.18. Sure, I could find that much under my couch cushions—but that’s not the point! The point is that I was able to build something online, put an ad up, and make money without having to do anything. I learned it was possible, and it motivated me to move forward.
Apple maintains it’s viral appeal, with the iPhone X through their launch of the "Selfies on iPhone X" campaign. The secret to this example of viral marketing (which has clocked up over millions views both online and offline) is very simple: a product so great that it turns people into fans of the brand all on its own. People love themselves. If they have the possibility of spreading this love digitally through selfies, it’s almost a guaranteed win. The iPhone X’s brilliant selfie feature spread virally through various media forms before apple repurposed the viral content into one masterpiece, the iPhone X selfies film. As one of the YouTube comments says, “It’s the most beautiful thing I’ve ever seen”… This viral marketing through video has allowed Apple to spread key features such as their Portrait Lighting effects and their TrueDepth camera.