Use Meta-tags effectively! Meta-tags are the first thing Search Engines SEE! It's important to your website Optimization.

 

Meta-tags are important to many search engines. While not all are still using them to categorize your website, many still use them to rank and prioritize your site. Meta-tags provide you the webmaster with a concise way of categorizing and defining your website. Don't believe that they aren't important, but proper usage is. Search engines have algorithms to prevent abuse and misleading information giving your site more weight. Don't cheat.

Keep META Tags Short But Concise

Don't use the description and keywords section of the meta-tags to give too much information. Realize that search engine databases are finite, and they do manage space. Keep your tags short and simple, and remember that search engines will penalize you for for misusing or overusing meta-tags.

Don't Use all CAPS!

While this used to work many years ago, it's just not true anymore. Search engines don't want to display information in all caps, anymore than you want to look at it. Rest assured that you WILL GET PENALIZED for using all caps, and just don't do it.
Avoid Doorway pages.

Doorway pages (Sometimes called bridge pages), redirect another user to a different page. These pages clutter up the search results and are really starting to upset people. You should note that using doorway pages is against Googles (and most SE's) terms of service. Doorway pages are mostly associated with the META Refresh Tag.

Don't say it again Sam!

Don't repeat the same keywords in the keyword or description sections of your meta-tags. If you need to, make sure they are separated by a few other keywords. Try to keep it light though.
Know what keywords are important to optimize your page!

Some search engines only read the first portion of your webpage. Make sure your keywords and descriptions are accurate.

Put meta-tags at the top

View the source of a couple of highly ranked websites and get an idea of what their meta-tags look like. No need to re-invent the wheel here. A meta-tag always goes in the same place above the body in the "head" tag.

Get help with meta-tags when you need it!
A great place to help you learn more about meta-tags is: http://www.submitcorner.com/ , they have tools to help you create great meta-tags, even a meta-tag analyzer.