Not sure whether to check your bag? The very first thing to do is to check with your airline and see the size and weight dimensions that are allowed for a carry-on. They are really enforcing this in 2026. The bag you got away with before may not work now. This especially goes for international travel. Many times, you will change planes to a regional carrier that will have more restrictions. Then measure your suitcase to make sure it is compliant.
As far as packing goes, it's easier to pack for a beach vacation than for a ski holiday. Many experts suggest you wear as much as possible, like your boots, sweater, and jacket. So far they aren't restricting clothing.
In deciding what to pack, of course think through the type of activities you will be doing and pack the basics. And layer for weather changes. Take a neutral color approach and then accessorize adding pops of color with scarves and jewelry. And pack with packing cubes. I love the ones from En Route as you can cram them full, add accessories in the lid and compress them down with the zipper. This keeps everything nicely folded and your suitcase tidy. I really dislike the folding and refolding before we used cubes. Plus, cubes keep your clean clothes separate from dirty ones. Miscellaneous items and shoes fill in the spaces between the cubes. For guys, who want to take at least one dress up shirt and tie, the cube is perfect in keeping it presentable.
Lastly, make sure your bag isn't too heavy for you to lift, especially in carry-on. Flight attendants are not required to help you.