I like the way you have listed the ways to earn extra income and was quite surprise that you did not make mention of network marketing, which is a way to make extra income without quitting your regular, though most people view mlm as a pyramid scheme but the real pyramid scheme is a regular 9 to 5, because you can only have one president of a company at any given time and network marketing business model to promote product that can be used is really cheap to join and can offer a substantial extra income or what do you think?
There are a few advantages to taking this approach. First, you get close to 100% of your listed price (minus the transaction fee of your preferred payment gateway). Second, you are not competing with other authors and have the reader’s attention solely on your product. Third, selling your eBook on your own platform is a great opportunity to build a long term relationship with your readers via email. Fourth, you can bundle your eBook with other goodies in order to bump up the value and make it more unique. With so many advantages, it's worth putting up the time and start building your own platform.

I personally haven’t tried any of the below methods so I can't speak from experience to how they work. In my mind, the most lucrative way is through building a REAL business online and providing your visitors with great value. However, after some thought, I decided to include these here because, quite often, the biggest roadblock for many is a mental one: believing that making money online is possible. From my experience, once you have made your first dollar, or even your first cent online, the world is suddenly a different color.
Inspired by you, I started a tax/personal finance a month ago. I figured if it works out, it will create a good side income for me. If not, at least I can use the blog to build my brand as a tax lawyer. Other than that, my current investment portfolio is heavily focused on index funds because of its historical performance and tax & cost efficiency. Right now my dividends income every year is about $14,000. I also have a good amount of unrealized capital gains every year from my investment, though I don’t count the capital gains as my passive income as they are paper gains, at least for now.
Hello from the UK! Fundrise and Wealthfront are only available to US residents it seems :(. Any other readers from the UK here? The only thing I have managed to do from Sam’s list is getting a fixed rate bond (CBS is having a 5-year fixed rate at 2.01% – not great but the best I could find ). Don’t know if the FIRE movement will ever take off here but would love to trade tips/ideas on how to reach FI and have the freedom to consider alternative rythms to living.
I've got a $185,000 CD generating 3% interest coming due. Although the return is low, it's guaranteed. The CD gave me the confidence to invest more aggressively in risk over the years. My online interest income has come down since I aggressively deployed some capital at the beginning of the year and again during the February market correction. You'll see these figures in my quarterly investment-income update.
Vanguard: Vanguard has a minimum of $50,000 and a fee of 0.3%. Rebalancing is done automatically once every quarter and tax loss harvesting is done on a client-by-client basis. We included Vanguard because clients who invest between $50,000-$500,000 have access to a team of financial advisors. Those with accounts over $500,000 will have a dedicated advisor.
* I use Personal Capital to track all my finances in one place. It’s much easier to use their free software to follow 28 accounts on one platform than to log into various accounts to check my balances. They’ve also got great tools for x-raying your portfolio for excessive fees, recommending a more optimized asset allocation, and planning for retirement with their Retirement Planner.