I like to use TC2 depending on the snow. If it's soft like sand, I feel that the TC2 lets the wheels keep spinning so that I don't get bogged down. What everyone said though is really good advice. The baby steps method I've used and it works well. If you start to lose traction, or can't gain any, sometimes turning the wheel back and forth will help. Sometimes if you're on a bump and you turn the wheel, you'll lose some resistance and start moving.
I'd say safe depths are (very low chance of getting stuck):
8-9" of hard, crusty snow (if you fall through anything deeper, you're SOL
)
15" of powder