What Do I do with a Keyword Niche?

After acquiring an extensive longtail keyword list, what method can be used to determine which of these keyphrases should be used on our websites?

• This question is solely based on the assumption we have already done our homework and have a stellar and very extensive keyword list. What "method" can be used in deciding which keyword(s) will out perform the other, similar niche keywords?   --------------------------------- METHOD EXAMPLE: Some of the keyword research tools have a KEI index.       The KEI compares the number of searches for a keyword with the number of  search results to pinpoint which keywords are most effective for your  campaign.   The formula for KEI is Searches * Searches  / Number of results. Suppose the number of searches for a keyword is 486 per month and Google  displays 214,234 results for that keyword. Then the ratio between the popularity  and competitiveness for that keyword is 486 * 486 divided by 214,234. In this  case, the KEI 1.10. The higher the KEI, the more popular your keywords are, and the less  competition they have. That means that you might have a better chance of getting  to the top of the search results. -------------------------------                           Preliminary Longtail Keyword Research: Here is a list of keyword research software tools, compiled from the that was provided for the question, http://1.%20http://www.seoquake.com/ http://2.%20http://www.link-assistant.com/rank-tracker/ http://3.%20http://ubersuggest.org/ http://4.%20http://www.google.com/insidesearch/index.html http://5.%20http://www.keyscouts.com/ Above links are a partial compilation of links found at the Quora Question:

• Answer:

  The most accurate ways of estimating organic search competitiveness I know of are: # allintitle: results x average Google PR of top 5 results Moz's keyword competition tool