This is a really quick tip. Before FCP X 10.2, there was a little + sign in the Inspector Color tab to add additional Corrections. With the changes to Color in 10.2, that little + is gone but… you don’t have to leave the inspector to add more corrections.
Apply your first correction to a selected clip via CMD-6. Make your adjustments. Then, in the Color Board, click the pop up menu in the upper right to add additional Color Effect instances. Easy.
Also, if you often make multiple corrections and want to set a bunch of masks before making adjustments, simply apply multiple “blank” Color Effects to a clip and save it as a preset. Apply it as needed and just delete the unused instances. Saves some clicking back and forth between panels. 🙂