Some tips from iLead on how to manage adwords;

Website performance measurement has seen a shift from visitor rates to the more indicative conversion rate. Advertisers try to attract visitors who are strong potential clients. This applies more-so to advertisers utilising pay-per-click marketing, where each click counts. Curious browsers, and unqualified visitors can be costly and diminish pay-per-click budgets. One way to minimise the number of low value clicks is to identify negative keywords. 

Google AdWords users are able to do this using the negative keywords tool.

Using the AdWords keyword tool begin by conducting a search for existing keywords, then use the “Possible Negative Keywords” function to produce a list of the most likely negative terms. Then indicate which keywords you wish to mark as negative.

Negative keywords are those words contained in a search phrase which you can identify as being un-applicable to your business for some reason. Once you have identified a keyword as negative, keyword searches containing these words will exclude your advertisement from listing thus helping you to avoid unnecessary clicks for products and services not available.

This is a useful cost management tool that requires once-off implementation and little effort.