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?
In these very tough economic times, it’s impossible to live comfortably and financially stable having only one source of income. To effectively mobilize your savings, investing is an ideal way to get in touch with. However, people usually invest and save the amount of money left after their consumption.  In simpler term, it’s impossible to invest and save before meeting your basic needs. This is just an implication that there is always a growing demand for making extra money and the use of residual income is one of the most effective ways on how to acquire this.
This one may seem simple, but that’s only because it is. If you were to move your savings from a traditional, brick-and-mortar bank with a low-interest rate and into a high-yield savings account online, over time you can make a surprising amount of extra cash. Online banks are FDIC-insured just like the traditional brick-and-mortar institutions, so your money is just as safe.
To create residual income, you need to create something that people will continue to buy on a regular basis long after you’ve created it. A house is a prime example of this as people will continue to pay rent for the right to live in the house. A business needs to have products that are sold over and over again rather than trading the business owner’s time for money.