Constantly keep learning and doing your best to understand more and more about blogging and convey important lessons to your audience and you'll succeed. Some of the most successful blogs in the world are earning millions of dollars per month. Don't expect that to happen right away. But that does show you the potential of what you can accomplish in this industry if you stick to it.
The funny thing is that all these things can happen. You could make a full-time income from building a blog. We do it, Corbett Barr does it, and so do many others. And you could become Internet famous like Leo Babauta or Chris Brogan. But if these are the sole reasons why you start blogging, you’ll be miserable, because it will seem like a job, and if it feels like a job you won’t be passionate about it, and so you’ll either (a) hate it, (b) fall flat on your face, or (c) hate it and fall flat on your face.
Working with advertising networks isn’t your only option when it comes to selling ads. If you end up with enough traffic, advertisers may come directly to you and ask you to place their ad on your site. You can also contact advertisers yourself. The biggest difference from the above mentioned option is that there is no middle man, which means you can set your own ad rates.