Campaigns on AdWords are designed to be small effectively written ads. Even though they are small they can be very effective in driving users tho your web site.
Two methods exist and they depend on where you are going to place your advertisement. During the set up process of the AdWords campaign you will be given a couple of options and you can decide to place your ad on the search or content network (Adsense) or you can place it on both networks.
Search network advertisements are assigned many keywords that would match the text of the advertisement and that is an excellent method for getting searches to locate your product or service.
Within the content network, as opposed to the other, your ad will be surrounded by an article or other content which is related. So in this scenario, your ad is viewed by readers who are maybe not thinking about purchasing at the moment, so, they are only browsing and not searching.
Because of this, contextual advertisements normally do not have the same impact as search advertisements. If your desire is to target both markets you want to create two separate marketing campaigns as this will allow you to expand your target area and inevitably increase traffic to your site.
Even though an ad put on a content network may not have as good of results as a search based ad, there are some positives about using contextual ads. The cost is lower per click and you usually have more control over where the ad is placed.
Even if you have already done advertising with AdWords you may want to begin a new campaign if you want to target the content advertising folks. It may be possible to use the same campaign on the content network but it might not be as effective since the audience is usually considered more passive.
In summary, a well-run campaign on a search network will generally be the best and most reliable way to generate business. However, with some cleverness and savvy and well-written copy, it is certainly possible that this could be supported by a complementary campaign running on the content network.