Wool against synthetics, what fabric weights actually mean, why next-to-skin fit matters more than thickness, and where flatlock seams earn their place.
Matching footwear to terrain, reading an outsole, deciding between a waterproof membrane and breathable mesh, and getting the fit right before you buy.
Heavy-duty locks, the two-lock method, choosing an anchor point, parking where it is visible, and registering the serial number before anything happens.