As Supergal and others have suggested, there are many ways to monetize your blog. However, just by putting a banner or an ad on your blog, without creating good regular content, building up a reader base and promoting your blog, you won't be able to earn much.
And yet, if you want to succeed, start working on your blog, write high-quality articles, interact with other bloggers, go social and build back links to your site. Then people will be looking for you and you will be able to convert your readers into customers. If you put a bunch of ads on your blog without having something valuable to offer to your readers, there is a high chance they won't return or even stay long in the first place.
Affiliate programs work best with blogs. At AffiliateCube.com we have many different offers that cover almost any possible sphere of interest. We are also a CPA (cost per action) model affiliate program. It means that if you have targeted traffic, you can choose exactly what you want to advertise on your site, thus eliminating ads that won't convert and having only those that will be attractive for your audience resulting in high EPC (earn per click).
Hope it helps and good luck!
