Meta Tags, and Alt tags and all those are all fine and work for the most part, but the best thing you can have in a website is meaty content. Content that enriches the keywords that are specific for your market; for the customers that you are trying to seek. It is extrememly beneficial to have at least 300 words per page of rich content. Now this doesn't mean just filling a page with all of your keywords and trying to make a story out of it. That doesn't work. Search engines have become very intelligent with the algorithims that have been created for them, and can detect much more that they could even 5 years ago.
Meta tags and descriptions are still useful without a doubt, but as many people have just stuffed countless, useless, keywords in them, their importance has dwindled. They are not weighed as heavily as they were when SEO started to become an imprtant thing with websites. Now it's all about your content.