You can make it hard way and check it manual in Google or go easy way and use software like SEOMoz. These scripts allow you to automatically keep track of your competition. They also have other built-in functions for SEO and are often options that allow you to manage your own link database. To beat competition you need to get knowledge about SEO, make practical test. You will always spend your time and your money to achieve results.
It really depends on what your looking for though .... If it's for PPC competition, you can use this: http://www.spyfu.com/ But, if it's for SEO, then just simply type up your keyword in the results and see who's in top
I think typing your keyword in the search bar in google is your best bet, if you want to find your keyword competitors