1. Use a raglan style cut with the bulk(needed to move) in the back and not in the breast area(all Cabelas, Bass Pro etc. is not made with this kind of cut)
Leave the shirts/jackets longer, best mid upper thigh to knee
p.e. graywolf woolens outfitter line uses this kind of cut
2. Buy top quality: cashmere,merino or loden fabric (no it is not $5/yard)...
3. Sew yourself, so you can accomodate to your figure, movement style, pocket position etc.
Before you cut the expensive fabric, sew up a mock garment out of some cheap cheese cloth and check for fit and movement
4. for ultimate warmth get a quivit vest or pullover
5. use a thin windshear layer
6. If you use coarser wool(like the one ron la clair uses, then use fine and soft merino or cashmere on the cuffs and around the neck area. That will not be scratchy in sensitive skin areas, even if you sweat or wipe sweat off your head..