If you're serious about making money online, start a blog. Blogging is one of the easiest and most sustainable income sources. As long as the blog is setup the right way, in the right niche, with the right content targeted at the right audience, and the offer is complementary to the content, you could make a tremendous amount of passive income from a blog.
Teaching and tutoring English as a second language is a great way to make money online, not to mention open some doors for you to travel the world if you'd like. While full ESL (English as a Second Language) accreditation is recommended, as long as you’re a native speaker and have the ability to teach, there are people in countries such as Hong Kong or the UAE who are willing to pay upwards of $25/hr for you to tutor them English via Skype. Check out Indeed, Learn4Good and Remote.co for remote english tutoring jobs or sign up on a specialized site like VerbalPlanet or Chegg Tutors.
If you don’t mind doing other people’s chores, then TaskRabbit is a great option for making money online. Earn extra income by walking your neighbor’s dog or mowing Mr. Smith’s lawn. It might seem like not the most lucrative option, but the top taskers reportedly earn as much as $7000 a month, making this a full-time way to make money online for some.
It can take time to build up your personal freelance business. Yet, there is more demand than ever for freelancers. So, if you want to kick start making money online through freelancing you can join one of the top freelance networks, such as Flexjobs, SolidGigs, Contena, Upwork, Fiverr, or PeoplePerHour. Sign up, build your profile, upload some samples of your work and start making extra money by doing small freelance jobs.