Since this Fall, I've had a twice-a-day, one-hour commute on a train. So naturally, the question emerged: how can I direct this time to writing music? My usual comfort zone centers around using the keyboard to find interesting harmonies with minimal notation. Thus, my train-time centers around using my inner ear to find interesting melodies with standard notation.
It's been very good training for having a better sense of line. By line, I mean horizontal continuity. The Prologue from Into the Woods has a tremendous sense of line, but let's not get ahead of ourselves. What path does, say, an 8-bar melody take from beginning to end? How big a harmonic space does it move through? Does it move swiftly or without assurance? Does it suggest its destination? Does it actually go there? Is it light or heavy? Does it seek variety or repetition? Does it even care? These are the sorts of choices that make a melody what it is (whether they're made by the composer or the melody is another question).
The homogeneous appearance of notes on a page can distract from these distinctions. It helps to find a way to embrace their actual heterogeneity, to get intimate with your materials. Synesthetic language admittedly doesn't translate well between people (hence the lack of examples here), but it's proven a good tool for this job. This much I can say without any confusion: there are profound possibilities in melody.