If you have an online blog on a specific topic or subject, then writing and publishing an ebook is one of the most effective ways to earn money. Websites like Nexus Notes or Stuvia let you upload your notes to sell. They only take a small amount, but you can earn an enormous amount. Make sure that your notes are written in a computer and not handwritten.
Renting out a room in your house or even just a portion of your garden can be an excellent option to earn additional income. You can advertise on sites like Airbnb or local classifieds, and word-of-mouth.
If you’ve got a knack for design Logo design is another way to earn money online. Just make sure it does not take over your life!