Adsense Optimisation: Help Google match Ads to keywords
If you’ve got Adsense on your website, you might have wondered how you can increase the click-through rate and increase you earnings. I had a site that was beginning to do pretty well in SERPs and serving up a few thousand pages a day but the click through rate was awful. I had with a similar site and a similar amount of traffic but his click-through rate was 3 or 4 times mine. His earning per click was also much higher.
The main thing I noticed about the Google Ads on my website was that the ads weren’t particularly relevant to the page on which they were shown, e.g. I might have a page about DJ/ Disc Jockey software but the ads would be for generic “free software”.
By doing some research on Google I soon found some information. I also did a bit of digging around in the PHP script I’d used for my site. I’d purchased the script but after setting up my Adsense ID, spent all my time concenrating on building links and traffic.
The first thing I found in the script was that one of the Adsense blocks used google_kw:
google_kw = “free software downloads”
At first, I thought this was the cause of my problems. Maybe this ad block was making Google serve up free software ads for all the blocks on each page.
I thought I could do a far better keyword match by coding the PHP to specify relevant keywords for each page. A little more research showed though that you had to have an Adsense Premium account, serving up 2,000,000 pages a month to use google_kw. Using google_kw without a premium account a) didn’t work; b) was against the Google TOS. So I removed google_kw and expected this would help make the ads perform better. After a day or two I noticed the click through rate was still poor and the ads were still not relevant to the pages.
The next thing I tried was using special sections to highlight to Google the content to use for matching ads. I put the following around the main, meaty content on the page:
<!-- google_ad_section_start -->
<!-- google_ad_section_end -->
Still no luck. A day or two later the click through was still poor and the ads were still mainly “free software” oriented. Then I had a thought - not only did I have to highlight the content, I had to tell Google to ignore the irrelevant content. Here’s a picture of a typical page on the site - the green rectangle shows the keyword-rich content, the red shows the content I needed Google to ignore. 
To help the user, I’d put a line of links back to previous levels along the top of each page. I’d put these links in bold to make them clearer to read. It’s also a good SEO strategy to bold hyperlinks too and I wanted my home page to be reinforced with the keywords “Free Software Downloads”. By the looks of it Google was seeing the bold text “Free Software Downloads” on the link and aiming most ads at this text. So I put the following around the line of links:
<!-- google_ad_section_start(weight=ignore) -->
<!-- google_ad_section_end -->
This did the trick, the ads were immediately more relevant to each page on the whole and the next day, the click through rate was 5 times the click-through rate before.