Here is what I wear. I start with one sweater and layer up if I'm cold.
First is a 100% lamb's wool sweater
Next layer is 100% wool in a larger size
Still cold I add my military sweater
Absolutely fridgid out there I add my vest. I know I look like a tick about to pop but this has kept me comfortable down to 13 degrees and that's about as cold as it gets here in my neck of the woods.
I could go with a bulky jacket but I hate the way the sleeve gets in the way of the bowstring. Even with everything on the layered sweater sleeves stay out of the way of the bowstring.
Total "keep me toasty package" was purchased at Goodwill for less than $10.