The PRE-CHORUS
The pre-chorus is a catchy area between the Verse and Chorus which sets up the chorus to be REALLY powerful. Here's a video from Weezer which have done a great job over the past 10 years making really strong songs. The Pre-chorus goes something like this...
Verse : Pre-Chorus : Verse2 : Pre-chorus2 : Chorus2 : Bridge : Pre-chorus3 : Chorus3
Sometimes there's a Chorus after the 1st Pre-Chorus, but use your best judgement of when it should come in. If done right, it sets up the Chorus to REALLY kick in compared to just going into it.
The REPEATED ENDING
The repeated ending. Some choruses aren't necessarily "Catchy" but written well, and with a repeated ending they can be the perfect fit to a song.
Here's an example from Radiohead using a live version of Karma Police. The song is really well written, but check out the ending how it basically is a repeated part, over and over and that its different from the chorus. Almost like a REALLY strong bridge that ends with that repeat. Very powerful when done right. Check it out...
