This should be the first tag of the head section of your code. The Document Type Definition Statement allows faster and deeper indexing with Google, shortening the time your site will be in the ?trustbox? as well. HTML 4.0 or 4.01 should be the standard, and for most cases, the Transitional type should be used.
The title, the most important.
Why? Because there are 3 elements in SEO: the listing (were title is the main element) the click-through (were title is the main reason) and conversion (which is the object of all optimization work) Also, if that is not reason enough (it should) it is the single element that gests indexed and used to list the link text in the Google SERPs (Search Engine Results Pages). An average of 7 to 8 words length is optimal.
The description.
Used by Google to create a text summary in describing the page if available, so make sure the content of this tag is friendly to the searcher, not the search engine. If you are in a competitive market, this tag is not taken into account, but you should have it for your visitor. An average length of 150 characters is good.
The keywords.
Google actually uses this tag against you, by that meaning it is used as a spam check point for the page content. Also, do not include your niche keywords here, as you will be given your competition tips about your optimization. Put your main keywords across the content instead. Here use an average of 200 characters.
Make sure you are using different sets of keywords per page, in other words, that they are unique to each particular page.
The charset type.
Another element of the head section, this one tells the browser what to do when it encounters certain characters in your pages. Google indexes pages easier with the 8859-1 tag, since it will not do any data encoding, which can take a lot of extra time. The UTF-8 tag involves encoding and it should be used for forms that accept non standard characters, like foreign users from other countries.
