* Investing: Twain was a notorious gambler and invested heavily in various schemes, including a typesetting machine called the Paige Compositor, which ultimately failed. This led to financial ruin for him in the 1890s.
* Publishing: He founded his own publishing company, Charles L. Webster & Company, but it struggled financially.
* Lectures: While a popular lecturer, Twain was known for his eccentricities, which sometimes alienated audiences and affected his income.
* Other Ventures: He also dabbled in various other ventures, such as a travel company and a mining company, which didn't bring him much success.
Overall, while Mark Twain was a successful writer, his financial life was a rollercoaster ride. He had periods of great wealth and periods of significant financial struggles, due in part to his risky investments and entrepreneurial endeavors.