A couple of years ago, I installed a single Google Adense skyscraper advert on each page. As others have mentioned, it doesn’t pay much more than a couple of beers a week. On a good month I’ll generate about $100/month from these adverts (which is, at least, enough to cover hosting costs).
I’ve had an RSS feed forever, I’m not sure it does a lot. I’ve recently put up a link allowing people to sign up for a newsletter. This mailing list has grown to about 750 recipients. Open rates on mailings are 30%-40% and click-through rate has a higher variance and ranges from 8%-20% (If you are going to experiment with email, I highly recommend a product called Sendy, it works great). Of course, I have a Facebook page to promote each article, and I also tweet a link to each article (where I have just a couple of thousand followers). The biggest generator of traffic is being featured on places like here on Hacker News, Reddit, or being featured on one of the large portals/news sites; these bring supernovae spikes in traffic for the time the links are in the sun. I also get a non-trivial amount of traffic from localized versions of my pages; People seem to like to translate my articles into foreign languages and usually put link-back credits, which is how I find out (I guess there could be people who do it without giving credit, and for those, I’m just ignorant about!)
I’ve embedded the occasional link to Amazon to allow users to purchase, if I mentioned a book I like. Amazon’s affiliate program gives me a small percentage cut of anything a user buys within a short time after following the link of my page. It works, and I get some revenue, but in total, it’s not yet broken $100 total lifetime earnings. As regards content, I try to publish a new article every week.
Bottom line - until I can get, at least, two orders of magnitude increase in traffic (or CPM), it will remain a hobby