Using targeted keywords is only the first step in coming up with profitable AdWords campaign. You should also consider the best mix and optimal keyword combinations that would ensure your ad appears in searches that are indeed relevant to your product and intended audience.

Use phrases. Using phrases instead of just words increases the likelihood of your ad being better targeted, as studies show that Web users mostly key in two or more words in queries, usually to limit the results, and arrive at better results. Even better, people usually key in phrases or questions.

Use keywords or phrases that people actually search for. Beware of being too specific or using keywords that are too obscure. These may bring in qualified visitors, but would be too limiting, especially if no one really searches using those exact words or phrases that you identify.

You can use the AdWords keyword tool (a sandbox edition for non-AdWords account holder is available here), or even the new Google Trends to choose among your intended keywords and determine which of these are popular in Google search queries. You can use these to compare across two or more keywords, so you can ensure that you use those that are more often queried.