AdWords works as a "bidding" system. The ad that brings most money to Google gets to be displayed (or actually the 4 best ones... or so).brbrSo if you have a 1$ click ad, but that only one per 1000 people click on, google will be better off with a 0.02$ ad that every second people click on.brbrSo you must build good ads. Other than, you have to choose your price - google will not 'do' it for you.brbrYou can setup a daily budget (i.e. no more than 5$ a day) which is always a good idea, just in case you do something horribly wrong.brbrThere's also a traffic estimator somewhere in AdWords, if memory serves.brbrI hope this helps... I'm not an AdWords master
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