It is a matter of everyone's thinking. But it is a fact that high competitive keywords or one word keyword takes a long time to get better or high rankings than that of the long tail keywords. But i do appropriate your heart to chose the competition and hard work to do.

Social bookmarking is very useful to get good links and traffic. Use long tail keyword for submission.

by doing social bookmarking you website will get huge traffic and yes do on high social bookmarking pages ..like stumbleupon,diigo,slashdot,redit etc

it's hug way of getting of traffic.

Social bookmarking are the easy off page seo tactic to create a inbound link.
I prefer short keyword yes it has high competition and high searches

Mostly short title are good....

Social Bookmarking is the best way that increase traffic and good back link...

very informative i've been using all those sosial bookmarking sites for almost 2 years now and doing great for my sites

social bookmarking is very useful for increasing traffic on you sites.it is a best way of get more and more back links.

Social bookmarking will help only when you have friends and followers

Social bookmark is most powerful link building way.

Social bookmarking is very popular link building procedure. For bookmarking submission, you can use one Keyword or long tail keyword depends upon the description. Your description must contain keyword.

It help to improve website ranking for any keywords, that you are using in Title for submissions.

Social media is the best way to get rank.

Social bookmarking is used to increase the traffic or visit of website if you want to know about keywords then you should target long tail keywords.