Really its just a matter of getting creative - grab a cup of caffeine and think for a minute about what resources you have to try to get some insight on your visitors (or target markets) and their needs before you dive in. Think about how much time it might take you (or what the cost of the reports would be if you are going to buy some market research reports), and tack that onto your billing as an optional service.
While I was doing WordPress speed optimization I noticed lots of people needed it, but very few people supplied it (there were a lack of services and tutorials when I researched Google). I also knew hosting was the #1 factor of website speed factor and these companies paid up to $200/sale. Hosting is a competitive space but the commissions and lack of supply enticed me.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.