A memorable tune has a shape. You can hear — and measure — the things that make it work: a mostly-stepwise line with a few well-placed leaps (and a step back to recover), a range you can sing (usually within an octave), and a single climax, the high point, saved for late. Build a melody, watch its contour and get a live critique, then develop it. For the transformation toolbox, see Composition Techniques.