it can be done to some extent by knowledge of proper keywords required according to the content of you website..for example..say you have a website related with photography..key word "photographs or photography" would be the main keyword and similar other keywords related to photography will be making it easy to be found through search if the users will be typing related keywords in search engines will be leading to your website visits of users..now if your traffic is also high which doesn't depend upon keyword listing but the content of your website then then it would be listed among the top..