Look in all Directions
If you want to capture some sunrise photos on Cadillac Mountain, make sure to check what the projected sunrise time is and knock off a few minutes from that because of the elevation. The sun also appears to rise sooner than it actually has due to atmospheric refraction where the light is being bent. You should arrive at least 30 minutes before, an hour is even better. Some of the best colors are realized by shooting before the sun actually rises in what is called the twilight period. Take a long a jacket because the wind can get pretty cool on top of the summit. When doing your photography, do not just look in the direction of the sunrise. There often are great shots perpendicular to the light.