It is important for good SEO to have page titles and descriptions. Page titles are generated by default with Drupal, but you need to install the Nodewords module to enable descriptions.

Download the Nodewords module from http://drupal.org/project/nodewords/. As usual, I got a big tar.gz file, which for me was nodewords-5.x-1.5.tar.gz. I uncompressed that into a "nodewords" folder on my harddrive with WinZip. I uploaded that whole folder to my Drupal server under the sites/all/modules directory. Next go into Administer >> Site Building >> Modules and enable Meta tags.

And now, when adding or editing any node I have a "Meta tags" link, which when clicked will let me add a meta description and meta keywords for any node.

While it is easier to think of keywords for any node, such as mispellings or related topics, don't spend too much time on keywords. Spend time on meta descriptions, as they are very important.