Case Schiller only tracks price appreciation of RE. RE as rental investment vehicle is measured primarily on rental yield or cap rate or some other measure. Price appreciation in that scenario is only a secondary means of growth, and arguably should be ignored as a predictor of returns when deciding on whether or not to invest in rentals. More important key performance indicators for rentals are net operating income and cash ROI. Appreciation, if it occurs, is a bonus.
Capital growth in your portfolio can offset the eroding effect of inflation.  But any capital gains that exceed the overall inflationary effect can be drawn off to augment your portfolio income.  Of course, you must first generate those gains by making thoughtful investment selections.  While allowing strongly growing assets to keep doing that, it is prudent not to allow them to become a dangerously large part of your portfolio lest they go off the boil.  So if you selectively trim profitable positions along the way, you can boost your income.
Although renting out your room or home can also be a side hustle to make extra cash, it's also a great source of passive income. However, another route to go is to get an income property just for the purpose of renting it out. This is even better if you live in a touristy area, because you can probably make even more than usual during the high tourist seasons.

Blogging – I guess you could say I’m a professional personal finance blogger since I own two sites and I’m making decent money every month. The income started off slow but has been consistently increasing. It’s not as much as I make with my day job but my best blogging month was equal to about one paycheck at my old day job.  While I had to learn how to set up and use WordPress myself, you can learn how to blog and make money online at
During my first year as a financial advisor, I got a small base salary. After that, it was up to me to figure out how to find and retain new clients. Fortunately, I quickly learned how to market myself, meet new people, and set myself up for success. And over time, I made the connections I needed to grow my base of clients, earn a real income, and produce the type of results my clients wanted.
Investing in rental properties: Another form of real estate investment, rental investments (i.e. becoming a landlord) could steer you down the passive income path of steady monthly rent checks that you can use to pay off a mortgage loan on the rental property. After the mortgage is paid off, those monthly checks go right into your bank account -- potentially for years to come. 
In addition to opening a brokerage account, you can also invest in peer-to-peer lending firms like Lending Club. I’ve been using Lending Club for a few years, and my net annualized return was 6.02% percent last year. Picking the right investments is easy since the platform offers automatic investing, but you can also pick your own notes if you're brave and want to learn the best ways to leverage the Lending Club platform.