Search for blogs that cover similar topics. Use a search engine and the search bar on blog hosting sites to find blogs that cover your topic or related topic. Read a few blog posts from the most popular ones, that show up high on the search ranking, have the most comments, or display a readership of 20,000 or more. Get an idea for how much interest and competition there is.
What is CPC? CPC stands for “cost per click.” By displaying CPC ads with Google Adsense, you receive a set fee every time an ad on your website is clicked by a visitor. The cost per click is set by the advertiser. (This is in contrast to CPM ads, where you’re paid for ad views instead of clicks. CPM means “cost per thousand impressions,” where M is the roman numeral for 1,000.)
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.