Using keyword tool is just a half of the story. You also need to make sure these keywords have a chance to score hign in search engines. Here's how it works: keywords with huge volume of searches not necessary will help you to get on top of the google. You need to choose hign volume searches words with low competition on the web. That's tough but possible. For example, keyword with 200,000 searches and 20mln competing sites will have no chance compare to keyword with 2,000 searches and only 20 competitiors. Its better to have 2000 visitors for right keyword than none if you are on page 200 of google.