It varies by how you learn, but I have found the Luminous Landscape Lightroom tutorials to be quite valuable.
I maintain a thread over in the New to Photography forum about what you can do with post processing. It's this one. Although most of this can be done starting from JPG files, it's definitely better to start from raw, which is what I do.
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!