The keywords for your site must be carefully selected as those which will activate your ad when the keyword is searched, but that not everything is so common as to be in the high competition. Some more specific keywords should also be included for each of your methods of payment on your ad by clicking. Each keyword is assigned a cost per click, or either depending on the supply that is paid everytime you click on the ad. The most common keywords in demand have a higher cost per click than the less common. Remember that it can take into account payment for service, and make that your customers can click on their ads which could increase the cost of the service in this case you have purchased. One of the biggest problems facing owners of web sites with a campaign of payment by clicking on your ad is fraud clicks. Fraud clicks can be avoided by his campaign’s payment provider by clicking on an advertisement, or by the use of specific applications against fraud which are easily found by searching for fraud of the click in a search engine. Carlos Gallego Google AdWords Expert if you want to get the free course, register at CarlosGallego.