Tracking your competitors is all important if you want to make your way up the search results.
SEO articles usually give a section on competitor tracking and saying you should, but why?
Your competitors or your successful competitors, will hopefully have put in the ground work for which keywords/phrases to use, which landing pages are the best to target, all on page optimisation covered on those landing pages, a blog to backup that landing page, articles out there for the landing page, which products they are promoting/stocking which you are not and the list goes on.
But the main thing to watch if nothing else, is the backlinks to your competitors and how they rank for those keywords.
All these backlinks will give an idea of the sites to get links from, how specific the theme of the backlinks to your theme of site and how much reciprocal linking they have.
This builds a picture of the activities of their SEO/SEM. Follow their lead, then 10% better your self.
Study your competitors and then plan your own campaign.