Forum Moderators: Robert Charlton & goodroi
I would suggest that you read this forum four times a day for an hour each time for the next two years.
Alternatively have a look at [searchengineworld.com...]
Also in the case of a large site, it is often worth looking at the robot accessibility. If you have large amounts of content behind JavaScript, Flash, redirects or 'dynamic' looking URLs then you might not be fully crawled.
If you want to target high competition phrases, then it's mostly about links. You want plenty of links from other sites, but even then it can take a while to see the benefits. Beware of taking shortcuts as Google penalise certain types of link building techniques.