Chickens will surprise you. They handle the cold much better than most humans. There are only a few things that you need to be extra cautious about during the winter in order for your chickens to stay healthy and happy. One is making sure they have water at all times, another is ventilation and third is food.
Unless you keep your chickens inside and use a timed lighting system, you are not going to get anywhere near as many eggs in the winter as you do in the summer. And, even if you do those things, you may being doing your hens a disservice because using a timed lighting system and keeping them unnaturally warm disrupts their natural rhythms. Also, you will have to continue to use lighting and heat all winter because the chickens will adapt to it and suffer if you stop.
It is normal for hens to lay fewer eggs in the fall and winter than during the rest of the year, so don't worry that there is something wrong if you aren't finding as many now as you were a few months ago.
The amount of extra work that will be required to properly care for your chickens in the winter depends in great part on where you live. If you live in an area where daytime temperatures are rarely below freezing, you will not have to worry so much about making sure your chickens have clean, thawed water to drink. If you live in an area where ice is a common problem throughout the winter, you may want to invest in a water warmer so that your chickens' water doesn't freeze.
Sometimes people worry about their chickens getting too cold and make the mistake of sealing up the coop to try and keep them warm. Your birds do need shelter from the wind, but they also need ventilation. In fact, a well ventilated coop is essential. Chicken manure contains high amounts of moisture and ammonia. Without good ventilation, the moisture will condense on the roof of the coop and drip down onto the chickens' heads. The ammonia can cause problems because chickens have sensitive respiratory systems.
Chickens have a built-in system for keeping warm. They, like most fowl, can fluff up their feathers, trap heat and stay warm and cozy. Some say that Silkies are not able to keep themselves warm because of their unusual feathers, but this has not been our experience. We here in Wisconsin have been able to raise Silkies successfully for many years.
While chickens generally don't mind the cold so much, they do mind being wet. Use extra straw or wood chips or whatever you use in the coop so that your birds' feet stay relatively dry. Try to keep the mud to a minimum in their run, or else lay straw there too. You wouldn't be able to stay warm while wearing a down jacket if your shoes were wet.
Finally, it is best to send chickens to bed with a full belly at night, so you may want to adjust your feeding schedule a bit. In order to give your birds plenty of exercise, you will want to scatter a light feeding through their run in the morning, then a heavy feeding in the afternoon. That way, when they roost at night they will have eaten plenty and digestion will help keep them warm while they sleep.