I've been commuting year round for about 10 years on GS's. It's not that pleasurable this time of year but it's better than being stuck for hours on the M6 car-park. I agree with what's been said by the others. Good riding kit is essential as is upgrading the lights, especially the dip as when this gets covered in salt spray seeing where road ahead goes when being dazzled by oncoming traffic becomes guesswork. Spots with the mainbeam make a heck of a difference if you are lucky enough to ride on a road quiet enough to actually use them
I don't use muffs, not for any particular reason as I find that Gortex ski gloves work well. Interestingly fitting winglets has kept my hands warmer as they must deflect the wind away from the bars somehow.
I'd not be too bothered with carrying spares (other than bulbs) if you have a rescue card. In 300,000 miles I've only had one puncture that deflated the tyre on-route and the BuMW kit fixed that enough to get me home.
Bodge up something you can use to wipe your visor as the salt spray will cover your visor on a regular basis, on bad days it'll get covered in crap every 10 miles or so. I use a bit of sponge jammed into a plastic bottle cable tied to the bars.
Other than that, take it easy in the dark and have fun!
