Keywords are what search engine look for when ranking your website. The greater the density of the keyword used in your websites, the more likely it will get a higher rank. While you are building your website, you may want to place the most important keywords in your domain name, title tags and throughout your sales copy. The important keywords that you chose play a critical role in SEO technology because there is a measurable indicator in SEO called KEI indicator, which means "Keywords Effectiveness Index", represent keywords with a combination of a high number of searches and a low amount of competing websites. KEI simply measure to allow you to quickly identify which keywords will give you the best results.
One of my favorite SEO analyzer by far has to be WordTracker. You can sign up for a free trail of WordTracker, although you are limited to 30 keywords and only 1 search engine in the trial version, it should be more than sufficient for any novice user.
Once you're logged into Wordtracker I recommend using the "Keyword Universe" to brainstorm for keywords. You just need to type in any keywords related to your area of interest in the left hand panel and then use the thesaurus to find related keywords and synonyms. Wordtracker returns 300 related keywords.
If you click on the keywords that you are interested one at a time you will see a list of searches that include this keyword phrase. Click on any keyword, Wordtracker returns 118 rows of keywords. If you like the look of any keywords you can just add them to my virtual basket and continue choosing keywords until you have about 100s of keywords and proceed on to the third step by clicking on "Competition Analysis".
At the competition analysis phase you will face with a number of search engines, directories and pay per click engines to choose from. I normally tend to just go for Google, since it represents near 50% of all searches. So, you select your preferred search engine directories and hit the proceed button, then wait for Wordtracker to return the competitive analysis from Google.