(1.) Your silhouette will slim down.
Fall's shapes are far narrower than spring's bubbles and trapezes. Marc Jacobs and Calvin Klein led the slim charge, with belted coats and tailored dresses respectively.
(2.) You'll channel the queen.
Tweed can be hard to pull off—it tends toward bulky, frumpy, and way too royal family. Thakoon handled it lightly on an elegant coat, while Ralph Lauren and Oscar de le Renta made it classic, not dowdy.