Keep description tag relevant - make it an "extension" of page's title. Do not loose track of this fact. It sounds obvious, but we see websites all time where webmasters are oblivious of this ! At same time, do not try to mislead potential visitors to your site - offer them exactly what they will find on web page. You will find that visitors become repeat visitors, as content remains King, and all this due to a well planned description tag.

Conclusion : 3 tags of a web page (title, description and keyword) goes hand in hand and supplement contents of a web page - see them as intertwined, and dependent on one another. If one of components don't fit perfectly into bigger picture, your web page is not optimized for search engines ..... period !

You can look at this page as if it was your sites yellow pages & index all in one. Imagine how difficult it would be for a person trying to find a specific stamp in a stamp catalogue with over 1500 pages. Let's add to this a few other volumes. Eg. 4 more volumes of 1500 pages each. Remember, you, webmaster might know your site plus it's structure, but a first time visitor doesn't ! Help them by having a good linking system between sections, as well as between various pages of a section. Also remember to include a link from all your pages to your main page.

Links to other important sections, like "about us" and "contact us" is always appreciated. Don't let you visitors go surf for it. Remember, you don't know though which page a visitor will enter you site, and first impressions normally last .... if visitor doesn't like page he lands on your site, he/she will surely not make any attempt to look further. You will loose a potential client.

Should you fail to properly structure and link your web pages, your site will become like a jungle : main sections bigger trees, pages little trees, paragraphs branches and information leaves. Your visitors will feel like a monkey let loose in a new forest ! Now go and properly re-structure your site. Thanks for your time.