The thing about color grading is that the longer you look at your photo the more your eyes will adjust. Meaning, you're going to start thinking that your grade is better than it actually is. To combat this you can take frequent breaks from looking at the screen. You can also use the wipe tool to aid you. This allows you to take any image or snapshot and quickly see it next to your own to compare. Especially handy if you want to imitate the colors of a particular photoshoot you've seen elsewhere.
In the Color Panel:
Wipe [Command + W ] this brings up a side by side comparison of your timeline and the first still grab in your Gallery (which is accessible in the upper left corner of the screen).
Reference Wipe [Option + W] Switches the default Horizontal still grab comparison from left to right. Vertical, Mix, Alpha, Difference and Box are also options located above the main window.
and as always [Command + , ] when it comes time to customize your own shortcuts!