How to find good keywords

Good keywords are frequently searched for (high demand) but not being targeted by many other websites (low competition). There are four tools out there that can help you find them.
Wordtracker - the best tool
Accessibility & CSS support packages
Get on-going help with:

•  Problem HTML and/or CSS code

•  Accessibility checking of new or existing pages

•  The writing of HTML/CSS code

 Training or advice on accessibility and/or CSS
 

The best tool out there, Wordtracker is one of the most essential SEO tools. To use Wordtracker:
Go to the Wordtracker website and pay ?7 for 24 hours access
Enter a keyword phrase you're thinking about targeting
Wordtracker will suggest hundreds of related phrases - click on the ones you like
Once you've clicked on all the phrases you like, run them through the program
Wordtracker will compile a score for each phrase, based on the number of users searching for it and the number of websites targeting it
The higher the score, the better the keyword phrase!
Wordtracker also offers a free service which works in the same way but only uses results generated from Altavista.
Other tools

Overture

Also useful, Overture's search term suggestion tool, is free and much quicker to use than Wordtracker. It works in much the same way as Wordtracker but doesn't tell you how many websites are targeting each keyword phrase.
Google
Google AdWords Keyword Suggestions tell you which keyword phrases are being targeted by other websites.
Guidebeam
Guidebeam is an interesting resource. Type in a phrase and it will suggest a large number of related searches. The numbers provided for each phrase are Guidebeam's estimation of how relevant that phrase is.