short tail keywords

I am looking to rank for a short tail keyword (2 words long), up till now I have target 3+ word, long tail words. Should I target a low competition short tail keyword? Why is this a bad a idea.

Hi All, Recently i have purchased KWFinder for my Amazon Affiliate website and am enquiring how to best utilise the keywords with low scores in reference to blogging? Obviously i'm trying to improve my SERPs on my blog articles, but haven't really stumbled across any detailed tutorials how to...