I've been using Google AdSense to monetize my blog and website for as long as I remember. In fact it is the first method that I've tried (I make $ whooping 15 on my first month ... back in 2005). Over the years I have migrated to other methods (eg, direct sponsorship and marketing affiliate), which makes AdSense a mere filler stock. I still make about $ 1,000 per month from it, but every time I can I will use another method on it.
Then a few months ago I started seeing the trend of increasing the CPC of my site, and I think that I have to give AdSense try again. I began to apply some tricks here and there, and next month I make more than $ 3,000 (which combines all of my sites). I was surprised, and I decided to keep using it actively in several sites.
In this article I want to share with you tips and tricks I used for my three AdSense earnings in a month.
1. I added the unit to my Big Website
Daily Blog Tips and Daily Tips for Writing is my website the biggest in terms of traffic. They are getting closer to one million monthly pageviews (combined). Despite that I do not use AdSense on them, especially because the direct sponsorship model works pretty well.
Several months ago I decided to load some AdSense units on site, however, and the results are very positive. About 70% of my produce to increase my income comes from the two sites. At the same time I managed to keep the other monetization methods work well, and readers never complained about the new ad (more on that later).
Even if your blog is already making money with direct sponsorship and marketing affiliates, therefore, you still can manage to increase your earnings by strategically adding multiple AdSense units.
2. I added the unit to my small sites
Like many webmasters, I have a lot of small websites scattered all over the web. Some free hosted platforms such as Blogger, and other self-hosted site that I left along the road. Most of these sites still get traffic, however. Not much, but combined to get a decent rate.
I think that adding AdSense units for all these sites can make money, and I was right. The main reason is that, because this is leaving the site and do not have loyal visitors, I can put the units are very aggressive. The result is a very high CTR (click-through rate), which compensates for minor traffic levels.
Do not underestimate the earning potential of small sites, especially if you are willing to place AdSense units aggressively.
3. I use the Big Unit
If you want to make money with AdSense you will need to use one of these units: rectangular 336 × 280 large rectangle 300 × 250, a skyscraper 120 × 600 large or leaderboard 728 × 90.
Every time I try to use a smaller unit results are disappointing. Even if my CTR is aggressively positioned too low.
All four units mentioned above can yield good results, but the best performance so far is 336 × 280 rectangle large, and that's what I used to increase my income.
4. I put the unit on top Fold
My first experiment was to place a 336 × 280 rectangle between the post and the comments section of my blog. The result is OK. I then decided to try putting them under the title of the post for one week, and the CTR is skyrocketing. In fact, I still need to find placements / combination unit that will beat the 336 × 280 unit placed under the post title.
I know this rule, but I guess I needed to test and get confirmation. The rule is: if you want to make money with Google AdSense, you must place the unit above the fold.
5. I'm Focusing on Organic Traffic
My main concern with adding a big AdSense units immediately below the title of my post is that some of the loyal readers can annoyed with it. At the same time I know that loyal readers become blind ads fast enough, and that most of my money will come from visitors organic (ie, people who come through a search engine for my post.)
To solve this problem I decided to show only a large rectangle on a post that is older than seven days (by using the Work Why WordPress plugin). It works like a charm, as loyal readers did not even notice the ad units when they are browsing through my latest posts, and organic visitors almost always see the ads because they are usually landed in the old post out of seven days.
6. I started using AdSense for Search
I'm not sure how much money I would be able to make with AdSense for Search, but I am not satisfied with search results provided by WordPress, so I decided to try it anyway.
Currently I make about $ 60 per month with AdSense for Search. It is not much, but if your number is more than one year we are talking about $ 720. On top of that relevant search results as you will get, so it is a win win situation.
7. I started using AdSense for Feeds
Other products I decided to try AdSense AdSense for Feeds is one. I choose to show ads under my feed items (you can also place them on top, but it would be too distracting in my opinion). The result here is quite good, both in terms of CTR and revenue.
You obviously need a large base of RSS subscribers to do this job, but I guess that even with several thousand subscribers, you can make $ 100 a month from ad feeds.
8. I toyed with section targeting
Targeting is a feature of AdSense that allows you to show certain parts of your site that should be used to match ads. You can read more about here.
I find that in a small niche and targeting of the website can help a lot. Many times Google shows ads that are not related on that site because there is no enough pages. After I managed to use section targeting to increase ad relevance and consequently CTR.
9. I tested with different Colors and Fonts
If you enabled both image and text ads on your unit should be able to customize the colors and fonts. I did some testing with both of these factors, and it helps to increase the numbers. Nothing dramatic, but it was definitely worth my time.
You just need to keep track of your CTR for several weeks. Then change the color or font and track it for another week, see if you can beat the original CTR. If you can, save the new format. If your performance decreases, try new color or font and track the CTR for another week, until you find the optimal combination.
On my site the best result comes from making ad units blend with the look of the site, but on some sites perform better color contrast, so the testing is a must.
Daniel is the owner of the Daily Blog Tips. He is also author of the ebook Make Money Blogging, which you can download for free by signing up for his newsletter.

source  http://www.problogger.net/archives/2010/02/08/9-tricks-i-used-to-triple-my-adsense-earnings-in-30-days/