Which (old) SEO methods should I ditch - and why?

Some say that SEO is all about content. Some say it's all about links.
I'm pretty sure that both are still pretty important.
However... every time people ask how to go about it, they are told to submit to search engines, have lots of meta keywords, update their submit to search engines, have lots of meta keywords, update their websites daily, etc etc
I kust wanted to ask
Which SEO tricks that were valid in -- say -- 2003 are no longer useful now?

From what I know, directory submissions are no longer useful. Links from footer and sidebar don't give as much as iside content links(guestposts). But overall you can't say that something is old and it's no use to spend a lot time on it, in my opinion you should spend the same amount of time and money on every aspect of SEO.