- Perform a naked search of the keyword e.g. “Organic Wine”.
- Perform an allinanchor search to distinguish the authority domains from the niche domains (allinanchor:”Organic Wine”)
- To get how many back links a site has using the keyword, perform a search using Yahoo! Site Explorer
- SEMRush competition meter. The higher the number, the more difficult it is.
Reference: http://www.seomoz.org/ugc/how-to-analyze-keyword-difficulty-tooless