keyword Selection TOOLS:
Google Adwords Keyword Tool
This is the fastest way to find keywords ideas for your main keyword. Just start typing your keyword in Google and it will automatically start giving you wonderful ideas.
Google Wonder Wheel
See visually how one keyword relates to other.
Google automatically gives related to data to a searcher:
YouTube Keyword Tool
It tells you how unrelated two keywords are in terms of its related search terms:
Ask is a great place to quickly find long tail keyword ideas or finding topics for articles:
This is a lightning fast way to get keyword ideas from all popular sources like Google, Wikipedia, ansers.com, YouTube, bing etc at the same time:
Twitter for Keyword Research
Good thing about using Twitter for keyword research is that it gives you ideas based on what people are saying NOW!