It may seem like melody writing is a gift, something you either have or your don’t, but it’s really not. There are guidelines you can follow that will help you in your quest for catchier themes. Here are just a few.
Make it singable
This is by far the most important principle. The reason great melodies are so memorable is because we can sing them. Great melodies are simple, and simple is singable. (Note that I said simple, not plain or dull. A great melody has to be interesting, but if it’s too complex people won’t be able to sing it and thus it won’t be as memorable.)
Stick to a scale
Choose a scale and use primarily notes from that scale for your melody. This will help keep your melody simple and singable. It’s always amazed me how catchy the Steely Dan song “Deacon Blues” is. The chords are all over the place, but the melody is simple and fluid. That’s because it uses only notes from the A minor scale (with an occasional Eb thrown in). If the melody followed the chords more closely, the song probably wouldn’t be singable at all, and would no doubt never have become a hit.
If you do use chromatic notes in your melody, it’s best to put them in unaccented and unimportant positions so they don’t have too much emphasis. Again, this will make your melody more singable and memorable. Listen to “Habanera” from Bizet’s Carmen for a great example of chromatic notes in a melody. Notice that all the chromatic notes are passing tones and none fall in places of stress in the melody.
More steps than leaps
From any given note in the melody, there are three options to get to the next note. You could stay in the same place (repeat the note), you could follow the scale up or down to the next diatonic note (move by a step), or you could jump by a third or more to another note in the scale (move by a leap). In the majority of cases, it’s best to move in stepwise fashion to keep your melody singable.
Leaps are exciting, and are often what gives a melody its interest, but if you load your melody with too many jumps it will no longer be singable and you can kiss that Best Original Score Oscar goodbye. One caveat, however, is that arpeggiations are generally much more singable than other types of leaps. To wit:
All of this is certainly not meant to discourage you from using leaps. Quite the contrary. A strategically placed jump here and there can add a real kick to a melody. The leaps in the first movement of Mozart’s Symphony No. 40 certainly prove that. But notice that most of the melody is made up of steps, and that the leap is a notable exception. This is what makes it such a treat—its uniqueness within the arc of the melody.
Use repetition sparingly
Like leaps, it’s best not to overuse repetitions. Too many repeated notes can result in a static, boring melody. As always though, there are exceptions. Here are two excellent examples of successfully-used repeated notes:
In both of these cases, notice that the repeated notes are followed by nicely-flowing melodies, effectively paying off the anticipation that the repetitions set up. And in the case of “Moonlight Sonata,” the accompaniment is so beautiful by itself that it easily sustains the listener’s interest while the melody is standing still.