Low Keyword Search Volume?
Outside of brand keywords, the most efficient keywords in any paid search campaign are product-specific, long-tail keywords. After launching these long-tail keywords, however, make sure to check your AdWords account for those keywords Google has rendered inactive due to inadequate search volume.
This Google policy has been in place for some time and can pose quite a problem for search marketers. In some cases, Google will map one of your other keywords to the long-tail query (sometimes relevant, sometimes not.)
There is no magic number of searches a keyword must receive in order to show, so don’t try spending two hours searching on the same keywords over and over again to try and increase the volume!
Fortunately, you do have a few options:
1) Try keyword insertion in your ad. This could improve the relevancy of your ad for the few searches there are.
2) To ensure that a relevant broad match result is served, you can either switch closely related ad groups’ keywords to phrase match, or add the low volume tail keywords as negatives to ad groups that might share the word in a keyword phrase.
written by Dennis Hayes -- dennis.hayes at channeladvisor.com