Tto help protect your eyes from cold drying wind wear a wrap around style of eye glasses or goggles. If visibility is limited by rain, poor light etc, consider wearing eye wear with yellow lens. You do want to have breakdown or flat due to something that could have been fixed before you left. It can be very uncomfortable and potentially injurious to be changing a flat or making adjustments in the cold or rain. Flats and breakdowns can still occur but don't set yourself up. - Fenders.
Many bikes can incorporate lightweight plastic fenders very easily.
Although it might not be cool or macho to ride a bike with fenders but if you ride a lot in the cold and wet you will learn to love your fenders. Many are easy to install and very light. Reducing or eliminating wheel spray will make your wet winter training much more tolerable. Even in the cold of winter it is important to drink and stay hydrated. Take plenty of water on your rides.