One of the most important ingredients of successful songs is repetition. Repetition is a key part of learning almost anything, so if you want someone to learn your song quickly, you can't afford not to use it.

Several studies have been made showing that most listeners have some resistance to hearing something unfamiliar. They'd rather hear a song they already know. It may be a little disappointing to learn that most people are so un-adventurous, but it's really not surprising: As writers and musicians, we are always looking for something fresh and new, and tend to forget that there's a public out there who, generally speaking, doesn't share that need for change. So they feel comfortable with the familiar, and uncomfortable with the unfamiliar.

This poses obvious problems for radio stations who'd like to add a new record by a new artist, but whose audience polls tell them they should keep playing established hits instead. The more they repeat those old songs, the more comfortable people feel with them, and the more personal nostalgia they generate. Since radio stations are relying more heavily on listener polls and feedback to program their music, and since listeners can't request what they haven't heard, new writer/artists are between a rock and a hard place.

If you can write songs for established artists, with already familiar and easily identifiable voices and styles, you have an edge, because a new and unfamiliar song by Christina Aguillera or Dixie Chicks or Allan Jackson is going to get played before an unfamiliar song by an unfamiliar artist.

Whether you're writing for yourself or someone else, you need to minimize the odds against you. Since your problem with a new song is to break through that resistance to something new, repetition of melodic themes, choruses or instrumental figures (riffs) will build instant familiarity into a song. Write a chorus that is totally and instantly understandable, simple, easily remembered and that touches their hearts and/or their feet. By the time the song is finished and the listeners have heard it three or four times, they'll know it and want to hear and sing it again.

The general objective is to have enough repetition without inducing boredom. It's sometimes difficult to determine how much is too much. Lyricists, in general, seem to get bored very quickly and even a very little repetition can make them feel guilty about not doing their job properly. On the other hand, a musician who's just found a great groove will tend to play it till the neighbors have him arrested. This supports the theory that you can get away with more repetition of a short lyric phrase if it's catchy and fun to sing, in other words, if it's "musical" by virtue of its meter, phrasing, rhythm, rhyme, assonance and alliteration. "Chattanooga Choo Choo," "Little Latin Lupe Lu," "Getting Jiggy Wit It," "Livin' La Vida Loca," and "Sk8er Boi" all have those "catchy" qualities about them.