The most important thing to do is to adjust your speed to the level of grip. So you need to drive very carefully.
Don´t brake late and hard, don´t accellerate too quickly either.
Make sure that you got a good distance to the car infront of you when your driving. You schould never trust other drivers, they might do the most unexpected. If he needs to brake hard, and you don´t got enough distance, you could end up chrasching into him.
But don´t be afraid to drive even though the roads are covered with ice, if you just take it easy it´s no problems.
It can sometimes even be rather funny!