Color Correcting & Color Grading
I found the free (and paid) tutorials at Color Grading Central very helpful.  Using a dedicated color grading application is (in my opinion) usually the way to go.  The basic version of Davinci Resolve is free, incredibly powerful, and offers a lot more control than grading in After Effects with plugins, in my experience.

For more on the theory of color grading, the Tao of Color Grading is a useful video on vimeo, (although the lighting is terrible). (part two is here).