"Keyword Density" is the name of the game with LinkedIn, as opposed to "keyword relevance", as practiced by Google. This is true with most internal search engines. There are several keyword tools available to help you decide which keywords work for you. If you are in need of a list, send an email to "firstname.lastname@example.org" and put "Keywords" in the subject line. I will then forward you a list of websites that will provide guidance for selecting keywords.