If you keep your money hidden in the attic or earning close to nothing in a savings account, you might want to consider putting it to better use through smarter stock investing as your side business idea. Sure, there are plenty dangers to look out for, but most personal finance experts will advise you to start learning about the stock market if you want to grow your wealth, and to avoid jumping too heavily into trends like Bitcoin and other cryptocurrencies without proper understanding.
Not only is Airbnb a great way to make money by renting out your spare bedroom or living room couch as a legitimate home-based business idea, but you also have the benefit of meeting new people and making new friends if that's your kind of thing. You can even rent out an entirely new apartment just to manage as an Airbnb side business idea, 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, you can take this business idea to the next level by offering your guests add-on and personalized experiences for an extra charge. Take Lauren Gheysens' Airbnb-based side business idea, Royal Day Out in London, England for example—where she gives visiting tourists a local's only tour of the city, complete with bespoke 18th century costumes.

Know someone who rents out property to others? Perhaps they could use a hand managing their property. If so, you can make a decent amount of money on this side business idea with relatively little work on your part (most of the time). It'll take some hustling and the willingness to be flexible with your schedule, as you'll be responsible for collecting rent checks, managing repairs and improvements, and simply being on call for emergencies. But, a property manager is essential for most real estate investors that have a large enough portfolio, so there's definitely merit to this business idea.
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