Interesting post on Gary Ewer’s WordPress blog. The author lists three common attributes of successful song melodies. Such melodies use notes traveling toward an apparent goal using mostly incremental changes (i.e., one full or half tone at a time) except during special words or phrases in the lyrics. These attributes make songs easier for audiences to sing and remember.
Some good points. Read in full:
Songwriting Tips and Tricks: Contouring a Melody