If you buy into all the hype, there are a million ways to make money online. After thinking this through, reading a bunch of books and articles, and finally giving it a go, I have boiled making money online to three steps.
First, sell something or provide a service people want or need. Yes you can make money from advertising or subscriptions, but after trying to I have come to the conclusion that in the end, the best way to make money online is to sell something or provide a service people want or need (or can be convinced they want or need).
Second, be good at what you do. If you provide a service, be as good as you can possibly be. No one buys from some one who sucks. If you provide a product, make sure it is a good one. Either make sure your supplier provides quality products or create a quality product yourself. In all instances just ask yourself that if you were in the market for your product or service, would you buy it and use it?
Third, market, market, and market. If you do not actively go out and do something to get attention (and page views) no one will know you exist. This can include anything you can do for free, or paying for some kind of service or advertising. The point is that no matter how successful you become, you never stop marketing because the moment you do, your business begins to die.
Everything else I have read is either a variation on these three points, or just hype in search of a dollar or two. Save yourself the wasted time and treasure and stick to the three I outlined above and you will be successful.
Just a note, not much has changed when it comes to making money. In the days before the internet these three steps were how you built a profitable business. What has changed is the medium. Instead of being fully physical (like having a store or an office), you can be fully digital. The steps still remain the same though.