ways to do keyword research for AdSense pages

1. If you have a Google AdWords account, pretend you are planning to advertise using different keywords, and see how much you'd have to pay. That will give you a good indication of the popularity of the keywords.
Here's how. Follow these steps. In step 2, "Create Ad Group", click on "Calculate Estimates" and "Recalculate Estimates". These show you the maximum you would have to pay per click to advertise for particular keywords or key phrases.
For finding new key phrases, you can use Go to Google's AdWords and find out how much advertisers are willing to pay for the keywords or key phrases you're interested in. Here's how.
Go to https://adwords.google.com/select/KeywordToolExternal and play around with the free Keyword Tool.
For example, try putting in a keyword or phrase, such as "book" and click on "Get More Keywords". Pretend you're willing to pay the maximum per click the tool allows - 100. (You can choose any currency. I chose US.)
Over on the right side of the page, make sure that "Cost and position estimates" is selected.
The tool will calculate for you the estimated average CPC (cost per click) for a whole lot of words and phrases. Try entering a different word, say "debt" or "free", click on "Re-calculate" and watch how the CPC changes.
You DON'T have to choose a topic which has expensive keywords. Often topics that have expensive keywords are very competitive. You may do better choosing a less competitive niche with cheaper keywords.

2. Have a look at the top 100 keywords on 7search. This will give you a quick idea of keywords that people are willing to pay big money for. You can also type phrases into the 7Search Keyword Suggestion Tool. This is just step one of your keyword research. You'll want to dig deeper.

3. At FindWhat pay-per-click search engine you can do a search for any phrase and quickly see how much advertisers are paying per click.

4. You can experiment typing words into Yahoo! Search Marketing's View Bids Tool. Let's say you type in "asbestos cancer". The top three advertisers often pay about $12 per click. So that might be an good choice for a topic - provided you're a specialist on mesothelioma AND provided that your research shows that it's an in-demand topic.
For "debt consolidation", the top two advertisers often pay more than $9 per click

5. The free Web Marketing Keyword Bid Research Tool speeds up your research at Yahoo! Search Marketing. Type in a keyword and learn how much advertisers are paying per click and also find out how many searches were done on that keyword last month.
However, you need to know that Yahoo! combines singular and plural phrases, and robots are used to check bids. Both of these factors tend to distort the results you'll see. Checking Yahoo! Search Marketing is good for quick, rough research, nothing more.

You want profitable keywords: high demand, low supply

Keep in mind that some topics attract much higher payouts per click than others.
For example, if your site is about topics such as debt consolidation, web hosting or asbestos-related cancer, you'll earn much more per click than if it's about free things.
On the other hand, if you concentrate only on top-paying keywords, you'll face an awful lot of tough competition.
What you want are keywords that are high in demand and low in supply.
So do some careful keyword research before you build your pages.

Affiliate programs versus AdSense earnings

Affiliate programs are often compared by looking at the EPC - earnings per click.
However, if you want to compare affiliate programs commissions with AdSense earnings, a more precise way is to calculate the payout you receive per 1,000 page views (CPM).
Here's how to calculate your CPM:
Let's say you earn $180 in affiliate commissions from 30 thousand (30,000) page views. $180 divided by 30 = $6. You have a CPM of $6. Not very inspiring, but not uncommon.
The AdSense stats display the effective CPM you earn.
Remember, AdSense doesn't have to replace your affiliate commissions. You can earn affiliate commissions AND AdSense commissions from the same page.
If you have a very efficient site with a high conversion rate, AdSense may not be right for you - or perhaps it would be suitable for SOME pages, but not others. Remember, the more choices you give people, the more likely you are to confuse them.
However, if you're creating a large information site, or if you have a site that does not have a brilliant conversion rate, AdSense could prove to be a very profitable addition to your site.
(Strictly speaking, CPM means COST per 1,000 impressions, but the calculation works OK whether you're spending money or earning it.)

Sites using AdSense

Sites using AdSense
Sites using AdSense include large information sites, affiliate-driven sites, forums and blogs.
"Chat" sites are considered not suitable. Some blogs are being rejected, but information-rich blogs are being accepted.
GoogleGuy explains AdSense
GoogleGuy, an anonymous Google employee who contributes to discussions on the WebMasterWorld.com forums, explains how AdSense will help information sites:
"...sites that provide solid content, especially niche sites that don't want to hunt down their own advertisers, should really benefit ... there's a whole universe of people who ... mostly produce informational sites, and the chance to recoup their costs without much effort is nice. I hope AdSense does encourage more diversity and voices on the web, because now smaller sites can work on what they're interested in - the content of their sites - without worrying very much about the costs of self-publishing information."
How to choose sites to block
You'll probably want to block some of the AdSense ads from appearing on your site. As well as blocking rubbishy sites, you may want to block tough competitors.
The ability to block sites is especially important for sites that are not purely affiliate-income driven. For example, if you're selling a service or a product you won't want competitors' ads on your site.
You can find such competitors by doing some searches on Google for key phrases that are important on your site and looking at the AdWords ads that appear.

Why are the wrong AdSense ads being displayed?

Sometimes, Google seems to get it wrong. You create a page and ads you've seen elsewhere and were expecting to see on your page just don't turn up. Instead, you see vaguely relevant or totally irrelevant ads.
Here are four possibilities:
1. Your page isn't perfectly optimized for the keywords. It's very important to get the key phrase in the file name, for example "product-xyz.html", in the title, in the heading, in the first paragraph, in the body, at the end, and put it in the meta tag description, too.
2. Advertisers can choose to advertise just on Google's search engine. They can opt out of advertising on the AdSense content network. Perhaps the advertisers you're interested in have opted out. To check, type a few phrases into Google and try to find some sites that are displaying Google ads and see which ads appear.
3. Advertisers can choose which countries will see their ads. If you're in Canada, for example, you may not see an ad that people in the U.S. will see. To find out where ads are being displayed, download the free Adsense Preview Tool.
4. This is very rare, but weird stuff can happen for no apparent reason. If all else fails, contact AdSense support. I've always found them prompt and helpful.

Will the AdSense ads appear on your page?

Publishers can choose to have their ads displayed only on Google or also on a large network of sites.
Will AdSense ads you see on Google appear your pages? To get an idea, find web pages that have material similar to the content you're planning to create and look at their AdSense ads.
You can also use AdSense's preview tool to see which ads are being displayed to people in different countries.
Beware: If you choose certain topics, Google will not allow you to place AdSense ads on your site and you'll miss out on a very lucrative opportunity.
Such topics include gambling, firearms, ammunition, balisongs, butterfly knives, and brass knuckles; beer or alcohol; tobacco or tobacco-related products; and prescription drugs.
For a full list of topics you may wish to avoid see: https://www.google.com/adsense/policies?hl=en_US

How AdSense matches ads to web pages

Google is doing a good job of finding ads that are highly relevant to the web pages.
Google says:
"We go beyond simple keyword matching to understand the context and content of web pages. Based on an algorithm that includes such factors as keyword analysis, word frequency, font size, and the overall link structure of the web, we know what a page is about, and can precisely match Google ads to each page."
Occasionally Google gets it wrong. It places great importance on the file name. So be sure to use important keywords in the file name of each page, such as "contextual-advertising.html" for an article on contextual advertising.
Also, watch out for your anchor text - the words in the links on your page. We've found that sometimes if irrelevant ads are being served, you can fix the problem by rewriting anchor text.
You can check the relevance of the ads by looking at the text ads near the top-right of this page