1. You can't do it all. You're going to want to go back.
2. Layers. Layers. Layers. The most I wore was a short sleeve t-shirt, a long sleeve sweatshirt, a sweater, a jacket and a rain parka over that. On other days, I was only in the short sleeves. It varied wildly. Don't plan on the weather at the ship being the same as the weather on your excursion. In Skagway, it was cold, rainy and overcast. As soon as we crossed the ridge into Canada, it was bright, sunny and warm. And we all left our sunglasses on the ship!
3. Prepare for rain. And remember, you can't control the weather, you can only control your attitude about the weather. A rainy day in Alaska on
DCL is better than a sunny day at home. It rained our entire cruise. It was still amazing.
4. Read trip reports to help you get ideas of things to do and see.
5. Don't limit yourself to DCL-only excursions.
6. Use space-saver packing bags to compress bulky items like sweatshirts and sweaters for easier packing.
7. Many people insist that a verandah is MANDATORY in Alaska but we absolutely loved our oceanview on deck 2. I loved sitting on the couch, being warm and watching the scenery go by right outside the window. If I wanted an outside view, deck 4 was only two flights away and decks 9 and 10 a quick elevator ride.