1, Do not rely 100% on weather forecasts, The accuracy of forecasts (for sunrise) might vary to a big extent even on two following days.
2, You can not have enough layers of clothes if you take photos on an island in winter. Count 4 layers for the upper body and add +2 to layers to it if you plan to stay outside for at least 90 min. Wear a full-body base layer.
3, Prepare for it that cold really kills batteries. Then do not be surprised if it kills it much faster as you
thought it would.
4, If it will be a windy day according to the weather forecast and you shoot on an island do not be too happy that it means clear skies. It actually means you freezing down to the bone.
5, Have a ready list of the places you want to take photos of already before starting the photo trip. Minus degrees and chilly wind are not best friends with random inspiration.
*Here you can read a useful article about how to prevent and treat frostbite: