It’s sometimes hard to comprehend just how much people love t-shirts. And with the right niche, marketing and tools, you can create an online t-shirt business that makes you extra money online while you sleep. (Even Bloomberg and Forbes feature stories from entrepreneurs who've done just that.) Services like TeeSpring make it easier than ever to create a t-shirt drop-shipping business where they handle the sales, printing, and shipping, and you’re only responsible for design and marketing. Or you can even buy into well-established franchise businesses like Rhea Lana that sell fashionable, affordable kids clothing and get the backing of a proven organization to fuel your online sales. For more tips, check out this simple guide to launching and marketing an online clothing store by my friends over at Selz.
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 Instash, Listverse, A List Apart, International Living, FundsforWriters, and Textbroker.
The audiobook industry is booming, yet only 5% of books ever get made into audio format. If you’ve got a background in acting, or if people have said you’ve got a voice made for the radio, you can make extra money recording audio versions of independent and popular books. Sites like ACX connect authors with audiobook performers. So, whether you’re an author looking for more ways to sell your book, or an actor/voice actor looking to make some extra income, you can sell your services online.
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. 
With drop shipping, you’re effectively partnering with a manufacturer or wholesaler to sell their products. This way, you don’t pay upfront costs to buy inventory, aren’t sitting on unsold items taking up expensive warehouse space, and don’t have to deal with shipping the products yourself. You simply create your site, fill it with drop shippable products, and drive in customers, with almost everything else done for you.