Watch out for 'sun strike' when the sun is low in the sky in the morning when rising, and late afternoon when setting. The sun can be so bright it is blinding and riders and drivers alike can not see or be seen!
Make sure you do a pre-ride check on your bike before going for a ride, particularly tyre pressures and that you have enough tyre tread depth (minimum is 1.5mm but more is recommended!)
Wear or bring layered clothing with you, and bring wet weather gear even if the sun is shining! Wet weather gear is essential in winter in case the weather changes quickly, and it provides another layer of warmth in cold weather as well as helping with wind chill.
Make sure your visor is clean and scratch free. Take visor cleaner and a cloth with you. Open a vent or open your visor just a little to keep the airflow and prevent fogging up. Pinlock visor inserts are very useful.
Invest in heated gear such as heated handlebar grips, seat warmers and a heated jacket and gloves. Getting too cold when riding means you lose the feel on your controls, and makes it difficult to control the bike smoothly if your extremeties like hands and fingers are too cold to move! The cold also makes you more tired and you can lose your concentration more easily.
Wearing high visibility clothing, and making your bike more visible by using lights, bright stickers etc will help you be seen easier (but no guarantees!) by other road users, especially on dull days and in low light.
The road surfaces in winter often stay wet, cold or damp and can become mossy or have leaves and other debris left on the surface from rain and wind. It is even more important to look further ahead when riding and scan your eyes across the road surface to give you time and distance to change your road position smoothly, avoiding poor or slippery road surfaces.
Focus on being even more smooth with your riding. Keeping your knees gripping the tank and your arms relaxed, head and eyes looking up and forward will help if you do lose traction.