Probably all already been covered but here goes with my personal winter checklist...
Get some decent warm winter kit, being cold = less concentration = great danger Jacket and trousers should have thermal lining no question and the best waterproofing you can afford, I wear waterproof overtrousers over my winter trousers if its raining makes a huge difference when its cold.
The weatherman is your friend keep a good eye on what is coming I try to avoid going out when the temperature gets near freezing especialy overnight as thats when you find the ice patches. if there is even a chance of snow bike stays in the garage !!
Always make sure your visor is clean it'll shed water easier and make sure your gloves have a fabric squeegy type fingers for clearing your view on the move (small damp chamy bar in a plastic bag tucked somewhere on the bike can be useful too for a quick stop and visor clean up)
get a snood / thermal head thingie with wind protection you will need it on colder days.
Gloves with cuffs that extend over sleeves and drawstrings to cut out drafts are a must.
I now install FogCity Anti Fog on all my visors.
Wear 2 pairs of socks !!
Always try and carry a spare pair of dry glooves !! Quick strategic stop and swap into dry gloves can be a godsend !
weirdly I always try and make sure I enjoy my winter rides I talk to myself a lot more about what I'm doing and what is going on around me. This works for me but its not for everyone. (am now certain of being earmarked for the men in white coats) Keeping positive instead of slipping into I'm cold and miserable mode is important.
Salt is evil and eats bike finish unbelievably quickly, rinse bike as often as possible after clean a wipe over with WD40 on a rag on metal bits will help protect them a little. (Forks, swingarm, wheel rims, casings)
If you can carry a spare layer of clothing in case you need it.
Being down South I can probably get away with more all year round riding but its true that its very good at teaching you restraint and better forward planning !!
keep everything you do smoother and slower than usual and cornering will be slower and more upright than in the dry and the lines you take will be different.
Make sure you have some Hi Vis / reflective stuff on your kit if its really bad you really want to give the best chance of being seen possible.
Hope some of that helps happy and safe all year riding to you.
JB