PS: my answer to this question is always… “the better question is… how can my blog help me build a profitable business?” Most of the profits from blogging are not made on your blog, but that’s okay. I don’t believe blogging about making money per se, but about branding yourself and positioning yourself within your niche market as an authority and leader. Once that is established, there are so many ways to move people into your money making enterprises. Email marketing, as you pointed out, is one of the best ways to do this. Sending people to your membership sites, services, info products and coaching programs are all great things to route people into as well.
SEO helps improve your website’s visibility in unpaid search engine rankings (also called organic results). If your website is placed higher in search engine results, you are more likely to receive increased traffic to your website. Knowledge of SEO will increase your traffic, thus bringing in readers and the potential to earn money through those readers.
Once you setup your account on AdSense you will be given a code to add to your blog. This code will automatically display advertisements on your blog from companies who are part of Google’s advertising network. You may see ads from small companies related to your topic, or you may see ads from large companies that are completely unrelated to your topic.