There are different user behaviors when they are looking for information online, searching and also action. But there are some basic category of keyword that can group segment of keywords into three type : Informational , Navigational and Transactional. I recommend to utilize all these keyword types into different stage of purchasing process.
Informational keywords are the keywords that user searching for general information, for example : weather, local guide , etc. For these keywords we can use to build up the brand awareness , branded sites can adapt the idea that generate good information in order create the favor and make the users return or recall the brand again when they are looking for specific information or products.
For this keyword type, we need to use the long tail content strategy to build the ton of contents in order to build the exposure when people searching topic related content and found our website that it might turn to our prospective customers, customers in the future.
Navigational Keywords are the keywords that user search for destination website instead of typing into Address bar. We can adapt this idea to steal the traffic away from destination site or competitor site by bidding those keywords.
For the navigational keywords, it always impact if we have very great offer deals advertise in the heat zone like top 3 ads.
Transactional keywords are the keywords that use for specific product , for example : "Canon EOS 500D Discount" , this kind of keyword will generate direct lead or sales which is highest value of keyword.