"Create your own products and services," financial blogger and life coach Michael Tamez tells Bustle. "Any company you could ever work for can replace you at any time. However, your individuality can never be replaced! I encourage you to explore your creative talents and abilities more. What are you good at? How can you monetize that talent and perhaps even build a business out of it? Have you experienced something extraordinary in your life, and because of it, have tons of knowledge and wisdom to share? ... Creating your own products and services can create steady streams of residual income, which pays you continuously, even when you're not working. Essentially, you bust your ass once and get paid for the rest of your life — even when you're sitting on the beach, sipping coconut rum. Just remember this: When you invest in your creative abilities, you become irreplaceable!"
There is no doubt that our grievances against the British Empire had a sound basis. As the painstaking statistical work of the Cambridge historian Angus Maddison has shown, India's share of world income collapsed from 22.6% in 1700, almost equal to Europe's share of 23.3% at that time, to as low as 3.8% in 1952. Indeed, at the beginning of the 20th century, "the brightest jewel in the British Crown" was the poorest country in the world in terms of per capita income.
The most liquid of the private investments are investing in equity or credit hedge funds, real estate funds, and private company funds. There will usually be 6 month – 3 year lockup periods. The least liquid of the private investments are when you invest directly into private companies yourself. You might not be able to get your money out for 5-10 years, depending on the success of the company and upcoming liquidity events.
If you have a blog or other type of site, you can build affiliate links to different services on the website. Many people use Amazon as an affiliate partner. For example, if you are a beauty blogger writing about different products, you can set up Amazon affiliate links on your blog so that whenever someone buys the product you mention on Amazon, you receive a percentage of the sale. Amazon is not the only affiliate partner out there. Here is good, in-depth information on affiliate marketing. 
Buy a small business: A local small business, like a car wash or a laundromat, is a great way to put money down on a money-making venture. Automate it so you don't have to be on the premises unless you're collecting money. Go into a local business with your eyes wide open - study the books, especially on income and expenses, and examine water and utility bills if your venture will be open 24 hours.
Track Your Wealth For Free: If you do nothing else, at the very least, sign up for Personal Capital’s free financial tools so you can track your net worth, analyze your investment portfolios for excessive fees, and run your financials through their fantastic Retirement Planning Calculator. Those who are on top of their finances build much greater wealth longer term than those who don’t. I’ve used Personal Capital since 2012. It’s the best free financial app out there to manage your money.
P.S. I also fail to understand your fascination with real estate. Granted we’ve had some impressive spikes along the way, especially with once in a life time bubble we just went through. But over the long term (see Case Shiller real estate chart for last 100 years ) real estate tends to just track inflation. Why would you sacrifice stock market returns for a vehicle that historically hasn’t shown a real return?
Others may define it more narrowly, but to me, PPC arbitrage basically involves setting up PPC ads (via Google AdWords or similar platform) and directing the traffic that results from ad clicks to a landing page or straight to an affiliate link (which many platforms don’t allow anymore).  The goal is obviously to earn more from the affiliate income than spent on the ad clicks.  You aren’t adding any value, but merely earning more from traffic than what it costs you to generate that traffic.

This would only require the investment of your time. Start with a blog on something you love. It could be anything. From a travel blog containing pictures of your travels to a sports blog dedicated to your favorite team/sport. You can blog about anything and everything. It doesn't matter. But write regularly! I've read that an online magazine editor would personally prefer someone who posts something daily over someone who writes long posts once or twice a week.
For a person working for a wage, their source of income is their job, or their labor (aka their time that they sell to someone). But you can own a house, and rent it out, and when your renters pay you renter every month, the source of that income check is your rental property, or your house. It would just be called rental income. If you have money in the bank in an account that pays interest, those interest payments are another source of income. We can say the source is interest payments, or we can identify the asset that is generating rent, and say your money in the bank that is generating “rent” (aka interest) is your source of income.