In order to really get a clear picture of your campaign effectiveness, you should have Google Analytics tags coded on your landing page. These tags will allow you to see where your visitors are coming from and which keywords they used. You can even link your Adwords campaign with your Analytics account and see actual conversion rate.
The goal of any online campaign is to achieve the highest possible conversion rate. Google makes it very simple to determine the conversion rate, but they don't guarantee ad results. The best performing ads, according to Google, are the ones that are extremely relevant to the search term and that have a compelling message on the landing page.
Your landing page, or the page that shows up if viewers click on your Adwords ad, should be clean and compelling. The landing page should drive a specific action like filling out a form or testing your product/service.
The key to a successful Adwords campaign is trial and error. You will need to test various keywords at various times of the day/week. You will also need to test variations of the ad copy to optimize clickthru and conversion rate. It all takes patience and a little bit of money and time.