I don't feel like Ive had a crack at this one yet. Maybe ive been missing them. I would go with some studded tires and a pare of barmits. Which are mittens that attach to the bars and keep your hands warm without keeping you from reaching your brake levers and shifters. There are lots of how-tos on both but that is most of what I do for my winter bike. Fenders are good if your riding in slush. Swapping to an appropriate chain lube for wet and salty conditions. Clean your chain and components a lot. They will rust faster with rode salt just like a car. If memory serves they sell weather proof chains that rust slower. But they run poorly so maybe skip that.