1. Don't go for a PR today!
It's slippery and there isn't as much room on the sidewalks and streets so take it easy and enjoy the run! Running in the snow is like running in sand on the beach. With every step, as your foot presses down, it actually pushes the snow (and sand) aside and only a small portion of the energy is used to move the body forward. So you end up with a shorter step and need to take more steps to cover the same distance. You will be able to follow your regular routes, but don't expect to go as fast as usual.
2. Protect Your Hands, Feet and Head.
I sound like my father: "wear a hat!!" As much as 30% of your body heat escapes through your head, hands and feet. Wear running gloves that wick moisture away. Try adding a wicking sock liner under a warm fleece or wool sock, but make sure you have enough room in your running shoes to accommodate these thicker socks. Stay away from cotton hats - they look cute, but will get wet and make you colder as you move along.
3. When in doubt, walk through an icy stretch.
It beats getting hurt slipping on ice. You can also slow down and use a gliding skating step as well.
Stay away from cotton! Start with a thin layer of synthetic material that wicks sweat from your body. An outer, breathable layer of nylon or Gore-Tex will help protect you against wind and precipitation, while still letting out heat and moisture to prevent overheating and chilling. As you move you will be creating your own wind chill, so make sure to be layered, but not over dressed, you can over heat.
It's cold and wet and there is plenty of moisture in the air, but you still need moisture in your body. Snow makes you work harder than you normally would, so don't forget to hydrate. It's easy to dehydrate in weather like this.
6. If you have them, try snow shoes.
They are an amazing workout and a great way to hit the forest preserves and trails.
7. Wear Reflective Gear.
It's snowy, dark and slippery outside. Reflective gear, light colored clothes, even reflective wrist bands are always a good idea.
8. Have fun.