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. 
Better yet, you can even upload your own book to one of the world’s largest book sellers: Amazon. With Amazon self-publishing, you set the price, retain the rights to your book, and get access to Amazon’s massive audience. For every sale, you keep 70% with Amazon taking the remainder as a fee. If you want to get started, check out Leslie Samuel's great guide to selling eBooks online or follow Tara Gentile on CreativeLive as she shows you how to use your existing body of work to write an eBook within the next week. Who knows, you might just write one of the best business books of this year!
Multi-vendor marketplaces, like ThemeForest, can be very successful. Chose a niche and create a vendor website for it. Your marketplace could be anything, from a platform for local artists to sell their work on, to an online digital product store. Once set up, invite people in that industry to sell their products on your site. You take a percentage of their profits when items sell.
Tools & Resources: I’ve written a pretty comprehensive guide on the best web design software that covers both free and premium software packages. If you’re serious about becoming a web designer, then I recommend purchasing the full Adobe Creative Cloud Suite. At $49.99 per month, this is probably a bargain considering what you can achieve with this set of tools.
Several websites offer money (after a minimum level of earning) by clicking on advertisements. Hence, they are called paid-to-click (PTC) sites. One has to get registered before the project begins. Not all of these sites could be genuine, so be careful. One may also refer friends and earn money in the process. Some such sites are ClixSense.com , BuxP and NeoBux are some of such PTC sites.
Offering specific online SEO services is also another online freelancer role that businesses are crying out for. If you know how to improve a website’s SEO by doing keyword research, creating content that can rank in search engines, adding metadata / schema to posts and pages, and building backlinks to a domain, to name a few tasks, then this could be a great line of work for you.
White labeling products involves purchasing pre-made products from a supplier and then adding your own labeling and branding. Products could range from candles to gym equipment or even tea, but all will come without labels, allowing you to create your own new range of merchandise. Most suppliers will advertise the fact they offer white labeled goods on their websites, so pick your niche and then find the right supplier and product for you. Once labeled, products can be sold via sites like eBay and Amazon, or from your own eCommerce store (discussed in a moment).