But don't make the mistake of thinking this will be a passive source of income—you're on call whenever you have a guest and you'll always need to keep the place clean for incoming visitors. On top of just renting on Airbnb, consider offering your guests paid add-ons, like Lauren Gheysens', Royal Day Out in London, England—where she gives visitors a local's only tour of the city, complete with bespoke 18th century costumes.
If you’re a fitness buff and have the right combination of charisma and business sense, working as a part-time online personal trainer can be both physically and financially rewarding. Once you build up a reputation and client base for yourself, it could easily turn into a full-time endeavor for you. Check out this interview with several fitness blog owners who are making a living online, from MonetizePros. As well, I'd recommend checking out this resource if you want to take this business idea seriously and get started with a business plan for your personal fitness trainer business today.
Consider your expertise. If you take the time to reflect on your experiences, you will realize that you have more knowledge about which to write than you might think. Begin by listing three assets that define you, such as your profession, a special hobby or a personality trait. Next, list three things that inspire you, such as religion, education or charity. Finally, list three of your dreams, such as getting married, traveling or spending more time with your children. These three lists should give you many ideas of topics about which you can write.
Don't sacrifice morals for a quick buck — At the outset, you'll want to do all sorts of things to make money online, but don't sacrifice your morals for a quick buck. Not only will you put people off, but you'll lose Google's trust. You also shouldn't concern yourself with things like Adsense or other ads on a blog before you have around 100,000 visitors per day. Yes, per day.
Start by taking other courses you’re interested in: Not only is this important competitor and opportunity analysis, but it also gives you an idea of how a course could or should look and feel. What’s the pacing like? Is it via email, video, in-person chats? Once you understand how you want your course to look, it’s time to decide what it should include. Those same courses are a great starting place. How can you make your course better or more interesting? Do you have experience others don’t?
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. 
If you've developed valuable skill sets or picked up certifications within your industry over the years, offering your consulting services to local business owners can be a lucrative way to make money online. Whether you're an expert marketer, business strategist, or manufacturing aficionado, there's likely a local business owner who's willing to pay you to help them solve an issue with their company. Start with this 18-step checklist to becoming a local business consultant from Karyn Greenstreet and then use my guide to crafting an effective cold email to convince them to hire you.
If you have your own eCommerce store, social media is the perfect platform to showcase your products. Demonstrate your products in use and tell your social following why they need to buy your merchandise. Most social media channels allow you to add ‘buy’ buttons your pages, allowing your followers to easily click through to your site and make a purchase.
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.
Last but not least, you can also earn money online by building an online community, although the monetization strategies you can pursue will vary a lot depending on your goals. You can build a community with a blog, for example. You can also build an online forum and charge people for membership. You could even build up a Facebook group and use your influence there to sell and promote products.