People are not always searching to buy. There are three different kind of keywords:
– keywords for browsing
– keywords for comparing
– keywords for buying
If you use keywords that are for browsing, won’t help you much. You might get high traffic but not high quality traffic. Not people who are ready to buy.
If you target keywords that are for comparing you will have a good chance to get the visitors you want. People who are using comparing keywords are looking to buy, looking for solution to their problems or reviews. These are the keywords you would want to target.
Keywords for buying are the exact name, model number or even serial number of a product. This is harder to target. Obviously individual product pages can be targeted this way but not the whole website.
For comparing, most people use a two to four word phrase. Single words are not targeted much. Visitors that are using more words are more likely to shop for goods or services than the ones who use fewer words.