Google's AdWords Keyword Planner tool is another common starting point for SEO keyword research. It not only suggests keywords and provides estimated search volume, but also predicts the cost of running paid campaigns for these terms. To determine volume for a particular keyword, be sure to set the Match Type to [Exact] and look under Local Monthly Searches. Remember that these represent total searches. Depending on your ranking and click-through rate, the actual number of visitors you achieve for these keywords will usually be much lower.

For example, assume your search ad generated 5,000 impressions in one day, of which 100 visitors have come to your site, and three have converted for a total profit (not revenue!) of $300. In this case, a single visitor for that keyword is worth $3 to your business. Those 5,000 impressions in 24 hours could generate a click-through rate of between 18-36% with a #1 ranking (see the Slingshot SEO study for more on potential click-through rates), which would mean 900-1800 visits per day, at $3 each, or between 1 and 2 million dollars per year. No wonder businesses love search marketing!
Within the results, Long Tail Pro inserted several more keywords based on that suggestion and automatically calculated all relevant stats (including KC Scores). It only took me a few seconds to scan those results and see a great long tail keyword – legitimate work from home jobs with no startup fee. This exact keyword gets 210 monthly searches and has a KC Score of only 25! Rosemarie could easily write an article for her Busy Budgeter site that is optimized for this exact keyword and she should be able to rank in Google somewhat easily.
The local data that is returned is a 12 month average of all search queries in the United States using the Google Search Engine and affiliated Google search properties. Using the sidebar on the left, marketers are easily able to specify the keyword matching type (Broad, Exact, Phrase), change the category, and refine their results to contain specific terms.
The limit on manual keywords could be higher.  I personally wish we could input 10,000 keywords at a time, instead of 200.  However, I understand the costs that Long Tail Pro has to maintain each time a new manual keyword is input.  Not a deal breaker, I just wish the limit was higher. (To be fair, I don't think most keyword tools have a bulk manual option at all).