A repeatable way of doing a thing. A method survives the person who used it, which is what separates it from a knack.
Greek methodos (a way of pursuing, a system), from meta (following after) plus hodos (a way, a road); a repeatable way of doing a thing, literally a road followed rather than a knack held once.
A way of doing that outlives whoever first did it — the difference between a method and a knack that dies with its owner.