Finding good keywords is one of the toughest tasks. When I do keyword research, I use 3 different tools. First, I use Market Samurai. It is a paid program, but the keyword research part of it is in the free version. After I've found a few ideas, I use Google Keyword Tool. You want to change it from "broad" to "exact" on the left side, and you want high competition. If you are looking to maximize earning potential, you also want cost per click to be above $1. It should be set default to local, but if not, change it. You want exact local monthly searches to be at 1600 or higher. Finally, use Google itself. Once you've narrowed down a few keywords, use allinurl:KEYWORD and allintitle:KEYWORD in a Google search. Good keywords will have both of these under 50,000.