From the Apple Color manual:
...On the other hand, there’s no reason you can’t distribute the steps outlined above among multiple rooms. This can serve to focus your efforts during each stage of the color correction process, and also provides a way of discretely organizing the adjustments you make, making each change easier to adjust later on. This section suggests but one out of countless ways in which the different rooms in Color can be used to perform the steps necessary to grade your projects.
Step 1: Optimize the exposure and color of each shot
You might start by optimizing each shot’s exposure and color in the Primary In room. As a way of prepping the project in advance of working with the client in a supervised session, you might restrict your adjustments to simply making each shot look as good as possible on its own by optimizing its exposure and balancing the color, regardless of the later steps you’ll perform.
Step 2: Balance every shot in a scene to have similar contrast and color balance
After optimizing each clip, you can balance the contrast and color of each shot to match the others in that scene using the first tab in the Secondaries room. If you select the Enable button of the Secondaries room without restricting the default settings of the HSL qualifiers, the adjustments you make are identical to those made in one of the Primary rooms. Important: If you’re using a secondary tab to affect the entire image, make sure the Previews tab is not the selected tab while you work. If the Previews tab is selected, the monitored image is modified by the selected Matte Preview Mode, and may exhibit a subtle color shift as a result while the Secondaries tab is selected. Clicking the Hue, Sat, or Lum Curve tabs, even though you’re not using them, lets you monitor the image correctly.
Step 3: Apply a creative look to the scene
Now that the shots have been optimized and the scenes balanced, you can focus on specific creative issues using tabs two through eight in the Secondaries room. You might use these tabs to apply a creative look, or you could go further and make specific digital relighting adjustments. At this point in the process, you can also use the Color FX room to further extend your creative possibilities.
Step 4: Make modifications due to client feedback
Once your client has had the opportunity to screen the nearly finished grade of the program, you’ll no doubt be given additional notes and feedback on your work. You can use the Primary Out room, which up until now has remained unused, to easily apply these final touches.
Moreover, because each step of the color grading process was performed in a specific room of the Color interface, it will hopefully be easier to identify which client notes correspond to the adjustments needing correction.
The steps outlined above are simply suggestions. With time, you’ll undoubtedly develop your own way of managing the different processes that go into grading programs in Color.
Sage advice, and not coincidentally identical with the color correction tutorials in The Guide that you can follow with either Colorista or Rebel CC, especially if you use the DV Rebel Tools.
I haven't talked much about the amazing DV Rebel Tools scripts that come with The Guide, but some enterprising Rebel Café denizens have created a New Colorista button and some examples of the thumbnail comp in action.
Apple's Color has a stillstore feature, but the stills you store are not live links to corrected clips on the timeline. If they were, and if you could tweak colors while viewing this thumbnail view, that would be awesome. For now, you'll need After Effects 7+ and DV Rebel Tools to enjoy that functionality.
The other important feature inherent in the idea of grading in layers is the ability to span a "look" across multiple shots. Again, this is relatively easy in AE using Adjustment Layers, and something I teach in The Guide. Color has the ability to share a correction across clips, but I think it only works with a whole "grade" (Color's name for an entire correction comprising all rooms), rather than, say, just the Primary Out. I'd love it if Color provided the ability to share the "look" correction between many clips while allowing the other rooms to be adjusted per-clip.
Hope you're listening, Apple. I know you're busy today!