My winter driving technique?
First, I need to say that by writing this post, I am in no part taking responsibility for anything that happens to you, your car, passengers, or innocent bystanders. If you choose to drive in slippery conditions, that is your decision and you are responsible for your own actions. If you crash, it is ultimately your fault. Know the limits of your driving skill and drive within them. Don't go full-send unless you're willing to accept the consequences if something goes wrong or you lose control of your car.
If it's seriously slippery and you're concerned about how much grip you'll have when launching from a stop, I do one simple thing:
Floor it, drop the clutch. The tires, limited-slip diff, and traction control do the job for you.
I then modulate the clutch and throttle as I get going to keep me going where I want to.
Outside of that, I just drive pretty normally.
If there was one thing I could suggest to anyone on how to extract the performance out of a car, it would be this:
Let the car do what the car wants to do. Do not fight it. Simply guide the car where you want it to go and let physics do the rest. As soon as you start fighting your car, you're going to go beyond the limits of friction and you could lose control. Relax, if the car wants to slide, let it slide. Keep the front wheels pointed where you want to go and don't stomp on the brakes.
This is a learned skill and can take a lot of time to get the knack of. For some people, it comes naturally, most people will never be able to fully grasp the concept. It's not a natural thing to do either, so it can be very tough.
Aside from saying that, I would suggest someone learn how the vehicle handles in slick conditions in a safe environment. Learn what you can and cannot do with the car. Learn its limits. Go to an empty parking lot and do some donuts, and try getting out of the spin while staying on the throttle. Then try to drive from one end to the other while keeping the car sideways the entire time, swinging from side to side. Try doing some figure-8's with the back end out.
The only way you'll get better at something like driving in snow and ice is by doing it.
The rest is confidence. If you don't feel comfortable driving in the snow or sliding the car around, don't.
Edited to add:
If I am driving on public roads and there are other cars around, or I'm not entirely sure about the grip conditions, I keep all nannies on, all the time. It's kicked in many times and probably saved my ass more than once. Even when climbing a hill, I have noticed TCS kick on.
If I want to intentionally slide the car around, and I'm not familiar with the environment or it's a relatively small space (I don't want to spin/kick the back out too far), I put it into Competitive Driving Mode (I assume Track mode in the C7 is similar).
If it's an open area and I feel comfortable with going all-out, I disable all of the nannies.