Notice that there is a center of gravity which is not the center of a thing, or a cross section which is thinner than the mean width, or a weak link in a strong chain, or a way of doing less work to achieve a worth while result where a great deal of complicated work needs to be done.
Strategy seems like magic as there is not a specific universal rule that can be taught or applied, it comes by undeceiving the self of true imperatives versus perceived impositions.
All this usually involves practiced familiarity with the pieces of a problem (which comes by experience or other learnings), applied in such a way that parts of the problem help solve the problem for you, while you conserve your efforts at every opportunity (as little expenditure as necessary.)