You can sell your ebooks through Amazon's Kindle program or Apple's iTunes Connect, which gives you access to a large majority of the digital-book reading market and the barriers for entry are incredibly low. You don't need to invest lots of money to make this happen, but you do need to invest lots of time, not only in writing the ebooks, but in marketing them as well.
Find a profitable niche. Starting with your interests, write down as many niche ideas as you can. Think about topics people might search online. Ideas include passions (like surfing or body building), fears (like spiders or speaking in front of crowds) and problems (like getting out of debt). Do keyword research to see it others are interested in the topic. Find out if a domain name is available that matches the keyword 100 percent. 
The music industry might not be as strong as it was in the 80s, but there are still plenty of ways to make money online as a musician. Sites like SoundBetter let you sell your services as a songwriter, producer, or session musician to thousands of customers a month. While Musicbed, Music Vine, Marmoset, and SongFreedom are perfect for licensing your music to TV shows, movies, and web series.
This is something like Experts Exchange, except that it’s more general in nature. As a professional in just about any field, you can offer your expertise on JustAnswer. They are looking for professionals in various fields who will provide answers to reader’s questions. You can make money online by answering these questions and pointing people in the right direction to get the solutions that they need.
If you are more confident in your skills, you can also market directly to websites and blogs. You can contact the sites by email to market your services. That will also enable you to select the specific types of sites that you are more comfortable working with. Since there are literally thousands of websites and blogs on the web, the potential market is limitless.
Amazon Mechanical Turk is a service that lets you make money online through doing paid microtasks. Each task is something simple that requires human interaction like rating search results, checking for the right spelling on search terms, categorizing the tone of an article, or even basic translating. You can do these tasks from anywhere you want and make money online from the world’s largest e-retailer.
In 2017, there were almost 90 million pet dogs in the US. Which has opened up a huge opportunity to make money online as a dog watcher or sitter. Specialized sites like Rover or Care.com connect pet owners with pet walkers, sitters, and boarding houses to help look after their best friends when they’re at work or on a trip. If you’re an animal lover, you can make extra money and get to spend some quality time with a furry friend.
Today, if you're at all serious about succeeding in any endeavor, whether online or offline, you have to deliver enormous amounts of value. Yes, you have to do the most amount of work for the least initial return. This is especially true online. Why? Because it takes time to build authority and create an audience, two primary ingredients necessary to succeed in the wonderful world of commerce on the web.
23. Affiliates – There are many affiliate networks, such as FlexOffers and CJ Affiliate that allow you to promote other people’s products and services. You simply put a link or a banner on your page and then you get a percentage if someone clicks through and buys the product/service. You’ll want to select products that are specifically within your blog’s category.This is an effective way to earn money once you have the traffic coming to your blog.
If you’re serious about making money selling things online, it’s pretty much impossible to not recommend Shopify. The platform gives you everything you need to get your online store up and running in less than a day including a custom domain, beautiful templates (so you don’t need design skills), secure payment options, and they can even take care of marketing and shipping for you. Whether you’re selling your own products, designs, or curating other products for people in your niche, Shopify is the best option for powering your online store.
Sponsored posts work much in the same way as paid guest posts, but they are posted by big businesses instead of individual bloggers. Therefore, the scope for fees is much higher, as businesses have larger marketing budgets than humble bloggers. Having sponsored posts by large companies will also help promote your site as reputable and as a leader in its field.
If you’ve got a way with words and expertise in a niche, there are plenty of sites that will pay for articles and content you write. Think of the sites you read regularly. What can you contribute to them that would be interesting? Research your niche and then look for ways to pitch articles. Many sites will simply have a submission or contact link in the footer. To get started, check out my full guide to becoming a freelance writer on the side and then submit your articles to places like Listverse, TopTenz, A List Apart, International Living, FundsforWriters, and Textbroker.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.