Keyword Selection and Competition checking

I would like to pay attention to Google Adwords External Keyword Tool.

It is maybe the best tool for keyword selection. You can see the search volume and competition for particular keyword or phrase. Combined with Google Trends you can make marketing research for any niche. Maybe thats the first thing to consider when you are going for a new site and optimization. A big limitation of this keyword tool is that you can view search volume of the current month only but sometimes thats enough to get a overall picture of the market situation.