I would say that long tail keywords are really too profitable these days, no doubt to it, if you find some long tail keywords then they are low competitive, but make sure that they have at least 1000 exact searches.
Speed: Thanks to the diminished competition, you don’t have to spend nearly half your life optimizing your site and building links before you can see your site ranking high for long-tail keywords.
Relevance: Since long-tail keywords are more often than not, specific strings of keywords with a several niche terms; the chances of then meeting the exact search needs of users are very high.
Conversion: The fact that search users will find sites targeting long-tail keywords more relevant contribute another point to chalk up in its favor.
Exposure: This is perhaps the least known advantage of targeting long-tail keywords. Using long tail keywords over a period of time will eventually help you rank higher for your head keywords as well. As your site gains authority and builds its trust quotient, the long-tail keywords will help provide enough targeted traffic and also enough ‘exposure’ to your head keywords that your attempt to target them alone won’t prove to be all that disastrous.
This is the time when we should use long tail keywords so that we don't have to build too many links, if you build a few links for your pages it would rank higher, all you have to know how to research low competitive keywords for better ranking in Google and other search engines.
Nowadays, Long tail keyword is important because the high competition keyword takes too much effort to index in search engines. Google also gave importance in a long tail keyword so concentrating this as well.
A long tail keyword is a keyword phrase that has very low search volume. Exactly what is considered low depends on your particular site and niche. I work with sites that consider anything over a dozen visits a month to be pretty darned good for one keyword, and a site that scoffs at anything below 1,000 visits a month. It all depends on your niche.
In statistics, the long tail is the large number of occurrences far from the "head" or central part of a distribution of popularities, probabilities or such. A probability distribution is said to have a long tail, if a larger share of population rests within its tail than would under a normal distribution. A long-tail distribution will arise with the inclusion of many values unusually far from the mean, which increase the magnitude of the skewness of the distribution.
The term long tail has gained popularity in recent times as describing the retailing strategy of selling a large number of unique items with relatively small quantities sold of each � usually in addition to selling fewer popular items in large quantities.