A great resource for any paid search advertiser is the Inside Adwords Blog, managed by Google employees. You can either visit the Blog often or request email updates, whenever a new post is made. This is a great way to find out about new services or opportunities with Adwords, downtime with reporting or data and user tips, tricks and tactics. It is very frequently updated, by the product and support people directly responsible for the Adwords platform. I highly recommend you put this site (email updates) into your paid search marketing arsenal – there is a lot to be gained from the information shared.
This recent blog posting provides valuable details regarding Google's Content Network:
"Contextual targeting on the content network happens at the ad group level, not at the keyword level. That means all the keywords in an ad group, along with the ad text, are evaluated when Google is deciding whether to show your ad on a specific content page. In other words, it's important for all the keywords in an ad group to belong to a common theme.
We recommend keeping separate campaigns for advertising on content and search. Please keep in mind that these tips below are specific to contextual targeting and advertising on the content network and may be different from your search network strategies.
Create a manageable, targeted keyword list.
Advertisers have found most success on the content network with ad groups of around 15 to 30 keywords.
Use tightly themed ad groups.
For contextual targeting, we look for pages that match most of the keywords in your ad group. For example, if your ad group has a number of keywords about lilies and tulips, we try to find pages about these two topics together. If you have an ad group with diverse keywords on different themes, it may decrease the number of pages on which your ad is likely to appear. When picking keywords, imagine what keywords would likely appear on the pages that you are trying to target, and create tightly themed ad groups around those keywords.
Use duplicate keywords for appropriate ad groups.
To continue the previous example, let's say you were creating a campaign for flowers and had ad groups for lilies, roses and tulips. Unlike search, we would recommend that the general keyword flowers be included in all three ad groups to help establish a floral theme.
Use ad group level URLs instead of keyword level URLs.
Because no one particular keyword is used to trigger your ads on the content network, keyword level URLs are not relevant. We recommend using ad group level URLs instead.
Measure content performance at the ad group level.
We've found that measuring your performance on the content network at the ad group level offers a better gauge of what strategies work best.
Build a comprehensive negative keyword list.
The more negative keywords you include on a particular topic, the less likely your ad is to appear on pages that match that topic. If a page is predominately about your negative keywords, while partially about your positive keywords, our system is not likely to show you on that page. If a page is principally about your positive keywords, but mentions a few negative keywords, then your ad may still appear on this page. We recommend that you include multiple negative keywords on topics you would like to avoid. If you sold camera film and wanted to reduce the likelihood of your ad showing on movie-related pages, you should include multiple negative keywords like -movie, -movies, as well as synonyms like -cinema, -cinemas."