Buy a tripod that extends to eye level without resort to a central column. The fewer leg extensions the better. Carbon fibre? It’s a lot of extra money for a relatively small weight saving; better go for a good alloy tripod (eg Gitzo 1340) and put the money saved towards a great tripod head.
A ball and socket head is the first choice for convenience, unless you are using very long telephotos, and the stability of Arca Swiss, Kirk and Really Right Stuff models can’t be faulted. If they are beyond your budget, look at pan and tilt models instead, with quick release platforms.
Ball and socket users benefit enormously from an “L” bracket that allows the camera to be mounted vertically, as well as horizontally, on the head. With this fitted to your camera, there’s no need to flip it on its side for vertical compositions. The best ones, engineered to fit particular camera models, are from Kirk and Really Right Stuff.
Graduated ND filters narrow the contrast range between foreground and sky, allowing detail to be rendered in both and were a mainstay of landscape photographers in the days of film. Given an uninterrupted horizon, they save time at the processing stage but are crude compared to the masking techniques now possible in Photoshop.
Head torch. If you plan to get to your location before dawn or return after dusk, you’ll need some hands free lighting. LED models are less battery hungry than those using incandescent bulbs.
Camera protection. A large carrier bag and rubber band to fix it around the lens will protect the camera from rain or snow.
A wide angle zoom. Frankly, the difference in optical quality between the best wide angle zooms (with Nano-Coating and low dispersion glass) and prime lenses is imperceptible, by eye at least. Unless you plan to make a lot of pictures in near darkness, a fast, f 2.8, lens is not really necessary equipment for winder landscapes; the best performance will normally be between f8 and 11 anyway.
A telephoto zoom. A 70 – 200 mm lens is a great tool for picking out details- and, if necessary, its range can be extended with a x1.4 converter with scarcely any loss of image quality. Make sure the lens has a revolving tripod collar; it takes the strain off the lens mount and makes vertical pictures a breeze.
And for you, if it’s cold: plenty of layers of warm clothing: polypropylene underclothes (NEVER cotton) to take sweat away from your skin to the outer layers; one or two layers of microfleece (not windproof, so that moisture can pass through); an outer shell of Goretex® or another breathable, waterproof membrane); a windproof fleece neckgaiter (it makes a huge difference if you can keep your neck warm); a fleece and Goretex cap; Ragwool or Thinsulate® and fleece mitts that can be folded back to let you use your fingers; for your feet, try a pair of Sorel boots in snowy conditions; they incorporate a thick felt liner that has kept my feet warm in minus 35 degree Celcius.
A flask with a hot drink. It is very easy to become dehydrated in winter without being aware of it, especially if you are carrying a lot of gear.
A large plastic sheet. If there is snow on the ground, this will save it getting amongst your gear when you put the bag down. On a sandy beach it is even more important that sand doesn’t get into the bag.