What are the best ways to make a sustainable income on the internet?

There are quite a few potential ways to build sustainable income streams online, but it does take consistent effort over time. Here are some options I'd recommend looking into:

Freelancing can be a very solid path if you have marketable skills like writing, programming, design, virtual assisting, etc. You can find freelance jobs and build a client base on sites like Upwork, Fiverr, and Freelancer.com. The key is building a strong portfolio and reputation.

If you have expertise in certain subjects or skills, online tutoring or teaching could work well too. Platforms like Chegg, VIPKid, and Outschool let you get paid to tutor students virtually.

Blogging and affiliate marketing are another possibility - start a blog on a topic you're knowledgeable about, produce great content, and monetize through affiliate programs, ads, and sponsorships over time as you build an audience.

Creating and selling digital products like ebooks, online courses, software, templates or designs through your own website or marketplaces is an option. It takes upfront effort but can generate passive income.

E-commerce by building an online store to sell physical products through platforms like Shopify, Amazon or eBay is one of the more involved but lucrative paths.

For more passive income, growing an audience on YouTube, Twitch or other streaming platforms by creating great video content and live streams that you can monetize through ads and sponsorships is an avenue to explore.

And for some extra side income, sites like Survey Junkie, Swagbucks, and Amazon MTurk let you earn a bit from online surveys and small paid tasks or "gigs."

The keys for any of these are finding income streams suited to your particular skills and interests, putting in the hard work upfront to build an audience or portfolio, and then actively marketing your products/services online over the long run. It takes real effort but can definitely turn into sustainable online income.