SEMRush - This site is a great way to figure out what keywords you need to start with, by stealing your competitors keyword building ideas.

SEM Rush is a great site and is VERY easy to use. I primarily use this to just dump as many keywords as possible from a competitor as well as a keyword check for my sites to see what my number is at each month. All you need to do is export the competitors keyword data into a spreadsheet, import it into a Google Doc Spreadsheet, and then narrow the keyword list down, removing the competitors brand names.