Newton's proof of the connection between elliptical orbits and inverse-square forces ranks among the "top ten" calculations in the history of science. This time-honored calculation is a highlight in an upper-level mechanics course. It would be worthwhile if students in introductory physics could prove the relation "elliptical orbit" [arrow right] 1/r[superscript 2] "force" without having to rely on upper-level mathematics. We introduce a simple procedure--Newton's Recipe--that allows students to readily and accurately deduce the algebraic form of force laws from a geometric analysis of orbit shapes.