You can use "AdWords" keyword tool as it is very fast and makes our doubts more clearer to keep our site on the top.
Just experiment with the tool to figure it out. Sometimes the main URL can be overrated. It might be good to help you rank for a keyword or set of keywords but these results that appear in this tool are for all those keywords and variations as in long tail searches
i usually combine google insigth to combine search volume patterns, google keyword tool and seoquake (plug in for mozilla)
Googles Keyword Tool is good, but don't use 'broad', use 'exact'. Another one that I have found to be useful is Market Samurai.
Everybody knows about the google keyword tool, now I use ezinearticle to get good keywords. Article marketing can help a lot.
I roughly recommend looking for keyword phrases with 2 to 3 keywords and the highest search counts. If you're in a local market remember to append the city name to your keyword phrases.