The title sounds cheesy, but it's a really good book in reality.
This is probably the most important book you'll read at your age:
Book link: http://www.amazon.com/The-Millionaire-Fastlane-Wealth-Lifeti...
Need - There has to be a need for what you're delivering. Don't blindly do what you love or are passionate about, do what the market requests. The market doesn't care at all about what you love, they care how you can solve their needs.
Entry - It shouldn't be easy to start the business/to step in the market. If it's to easy to get into the market, it's probably way harder to succeed in that market. There's a reason why it's almost impossible for blogs to earn serious money, it's simply too easy to start one. Everyone can start one. If everyone can start up a clone of your business, it's not likely to succeed. However, if it takes some real work/investment to startup your business, it's probably a better business.
Control - You must be in control over your own business success. If somebody else can shut down your business, you're not in control. If your business is relying on API access or affiliate income from somebody else, it's not a very substainable business.
Scale - The business must be able to scale to the masses. If you're running a sandwitch cart, it doesn't matter how good your sandwitches are. You can't suddently sell 100 000 sandwitches in a day in your neighboorhood. However, if you're selling access to something online the whole world is your market and it doesn't cost you much more to sell 10000 subscriptions than it does to sell 10.
Time - The business success needs to be seperated from your time. If the business can't grow seperated from your time , it's not really a business. It's just a job you have created yourself. This doesn't mean that you shouldn't spend a lot of your time on your business, it just means that what your business earn shouldn't be connected to how much time you spend running it.
Read the book, it's really good (71 five stars/1 four stars/0 three-two-one stars).
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