Therefore, the foremost step in any SEO campaign is identifying your target audience and researching what keyword phrases they might be searching in the search engines to locate a site like yours.

If you would like to create a website about traveling you could optimize your site for the generic term "travel", but how well is that going to perform?

Well according to Overture, 2195206 searches were performed for "travel" in Dec 2005. Now in order to rank high for this term you would have to compete with high end websites such as travel.com, travelocity.com.

Now that might be your ultimate goal but if you are just starting, there is little to no chance you will be ranked high enough to receive any traffic for the term.
 

If you were to do a little keyword research, you might find more specific terms with much less competition like "group travel" 15002 with searches, or "travel destination" with 16706 searches, or "travel inn" with 13338 searches. Obviously, the number of searches is much less with these phrases but your chances of ranking high will be much more.

Searching Keywords : One way of searching for keywords is to focus on identifying as many keywords as possible that are related to your website and target audience. It is a good idea to start with identifying 100 to 150 keywords related to subject of your websites. Alternatively you can start with 10 t0 15 generic terms and latter expending them into keywords with the help of top and reliable keyword research tools and software / services.
 

The most generic keywords are the most widely searched, but also the most competitive and sometimes bring mediocre conversion rates. So my take is to search for little less competitive keywords tightly describing theme of your website.

Keyword Research tools like Wordtracker and Google Keyword Tool can be used to expand on your initial list of starting out keywords. These tools allow you to find the number of searches being made on a particular term and also look for all related terms that include your search term.

Wordtracker and Google Keyword Tool are the two most widely used services that give you the ability to research and find out what people are actually searching for on the major search engines along with information on how popular a search term was in the last 30 or 60 days.