I have started more than 30 projects so far.
2 projects stand the test of time. The income has been gradually going up and does not show any signs of going down in the near future.
All the other projects lost its effectiveness and had to be let go.
Those 2 projects were based on content.
So it all comes down to this: CONTENT IS KING.
And of course you have to market your content too... but after a while it can generate a momentum and does not need the push.
I guess one cannot go wrong creating content.
There are many other successful methods of making money online - I don't disagree with it.
Content - its the foundation of internet. Foundation for your own business too.
Even if your business is selling some services - marketing it with content will give a steady flow of genuine customers.