Most "layering guides" just tell you to wear more clothes. That's not a formula, that's a way to look like a duvet with legs. The actual skill is knowing which three pieces do the work, so you're not wearing five.
A denim outer layer over a single mid-weight piece. No bulk, still warm to -2°C.
Start with a base that actually breathes
Cotton against skin holds moisture and goes cold the second you stop moving, whether that's the bus stop on Corporation Street or the walk back from Digbeth. A midweight merino or brushed-cotton base layer regulates instead of just insulating, which is the entire reason it can replace two thinner layers instead of adding a third.
The mid-layer is where most people overdo it
One structured mid-layer, not two thin ones. A single quilted or brushed-fleece piece traps more warmth than a t-shirt and a jumper stacked on top of each other, because dead air space, not fabric count, is what actually insulates. This is also the piece that should carry your silhouette, since everything else is either invisible or minimal.
Base: brushed cotton or merino
Sits close to skin, wicks instead of holding damp, disappears under everything else.
Mid: one structured piece
Quilted overshirt or heavyweight fleece. This is the layer people actually see.
Outer: raw or waxed denim
Blocks wind, takes the weather, ages into something better than new.
One outer layer, not three
A waxed or raw denim jacket does the job a puffer, a scarf and a second jumper are usually drafted in to do badly. It blocks wind at the collar and cuff, which is where most of the heat loss actually happens, and it's the one piece in the stack that's supposed to show wear over a season rather than look brand new in every photo.
The 3-Piece Capsule
Base, mid, outer: the exact pieces from this guide, bundled at 15% off through October.
The 3-piece capsule that covers October to March
Buy for the coldest week you'll actually leave the house in, not the coldest week on the forecast. One base, one mid, one outer, worn in different combinations, will outlast a wardrobe of "seasonal" pieces bought one panic-purchase at a time, and it'll look like it was chosen on purpose because it was.