This is the fourth and last article in a series that guides you in using Google AdWords. In this article we'll cover keyword strategy, taking a look at the use of negative keywords; consider the AdWords contextual network; and see how to use image and banner ads.As you learned in the previous articles, targeted keywords, a good advertisement and persuasive landing pages are the three aspects that help you make money with AdWords. The entire AdWords campaign is broken if even one of these elements does not work.
In the two previous articles we discussed in detail ad creation, ad writing and landing pages. In this article we will study an effective AdWords keyword strategy in depth. It will help you lower costs per click, get a higher click through rate, get more traffic and raise your quality score. We will discuss Google's contextual network, its effectiveness and whether you should opt out. And in the end we touch on another AdWords segment - image (banner) advertising, its effectiveness and banner strategies.
AdWords Keyword Strategy
As you start a new AdWords campaign, you won't know which keywords will bring you the most traffic and generate the most conversions. You can guess, but the only way to find out is to let the ads run for few days.
Take your core keywords (you can read more about this topic in the previous article) and create an ad group for each. Each core keyword requires a separate group and a separate ad.
Put secondary key phrases into an ad group according to the core keyword to which they relate. For example, if the core keyword is "buy digital camera" and secondary keywords are "buy cheap digital camera," "buy panasonic digital camera" and "buy digital video camera," then those phrases will go into the "buy digital camera" group. (We discussed keyword research in detail in the second article in this series).
Write two ads for each ad group in order to do split testing.
Put conversion tracking codes into the appropriate pages to track the sales each keyword delivers. With conversion tracking, AdWords will report the number of clicks, impressions and conversion rate for your phrases.
Let the ads run for a few days.
As the advertisements run on search results and on the contextual network (more on the contextual network later in this article) for different keywords, AdWords collect statistics. After a few days you will have good performance data for each ad group. This is what we're after.
Once you have the statistics, you will notice that some keywords drive way more traffic than the others. Take those keywords and put them into their own ad group.
This will help you lower your cost per click, increase the click through rate and raise your quality score, because when you put keywords into their own ad groups, you will write new advertisements for each, designed just for those keywords.
With this strategy you will:
Lower the price you pay for each click. Google rewards advertisers that have a high click through rate by lowering their price per click and moving the ad into a higher position.
Get more visitors to your website, and more conversions as a result (assuming your landing pages do the job).
Increase your AdWords quality score.
Notice that when you stick high-performing keywords in their own ad group and write an advertisement specifically for those phrases, your overall click-through goes up.
Google Optimization 
