This is very good advice for most entrepreneurs and self employed people. Thank you for writing this up.
Multiple cash flow streams is key to diversify your income portfolios.
One caveat is the advice regarding the stock market and fixed income investments. Timing of purchases and sales is very important in this case, and even though logic says to buy low and sell high, it is often the opposite that happens.
I think more people should look into rule based trading and alternative charting methods beside the candlestick charts. Fractals (trend reversal price points), support/resistance levels and Fibonacci levels must be understood and respected.
Also, real estate can also be a good investment if it returns a decent positive cap rate.