From all I know about blogging, "easy" is quite an exaggeration unless you live in rural China. Blogging is a hugely unreliable source of income unless you're a blackhat SEO. It's strictly possible to make a decent living, but the odds are worse than almost any other profession. Your chance of making $10 per month is vastly higher than your odds of making even $1000 per month.
I'm looking at doing a webcomic. There are webcomics that support themselves. I do not know of details on exactly how they do that. I have looked at some webcomics that support the author and they have ads, sell t-shirts, take donations, etc. I would still be interested in seeing any articles with harder info that anyone might happen to know of.
Zach Weiner of SMBC-Comics.com did an AMA on reddit and said that he makes a living off of, "Mostly ads, though t-shirts sales are a decent percentage as well" [1]. He lists the ad networks he uses in the AMA.
You could try asking him for more specifics; he seems pretty friendly and open.
The percentage breakdown varies, by comic. Something Positive was apparently making 35% of its income from ads [2]. Dominic Deegan's artist "makes most of his income selling self-published compilations of his webcomic at anime and comic conventions" [2]. I've also read of other artists—can't remember which, sorry—saying they make little through ads, and that most of their income came from merchandise sales.
