Continuing the discussion from How long should chord progressions be?:
There are many different ways that songs transition between different sections (verse, chorus etc). While there is no right or wrong way to do this, here are a few tips to get you started:
1) Try ending one section with a chord that cadences to the next section. For example, if your chorus starts on a I chord, try ending your verse/pre-chorus on a IV or V chord. This will create a natural anticipation for the I chord which will bridge the two sections. See for example the verse of Aerosmith's Don't Wanna Miss A Thing:
If your chorus starts on a different chord than the verse, say vi for example, you can use a cadence chord of vi, such as V/vi, ii, or iii to bridge the sections. In the following example from O-Town's The Painter, the intro and chorus start on I, but the verse starts on vi. They handle this by using a V/vi chord to transitioning from the intro to the verse, and a V chord when transitioning from the verse to the chorus.
2) Some songwriters prefer having different sections of a song sound very different. Some songs, for instance will use only 1 or 2 chords in the verse, whereas the chorus has a much more diverse chord progression. In these cases, the new harmony introduced in a new section can create a fresh sound, and the actual transition between sections is less important. In Katy Perry's ET, the verse only uses one chord. When the pre-chorus comes in, she introduces 4 additional chords that gives the song a new feel. This song does one other interesting thing: the final chord of the pre-chorus is a V/vi, which makes the listener expect a vi chord. Instead, the chorus starts on a IV. This is known as a "deceptive cadence" that we will discuss more in the second Hooktheory book.
3) Ultimately, your ear is your best guide. Sometimes songs just seem to work, even if it looks like they won't on paper. Remember, songs are much more than their chord progressions and melody; instrumentation, vocals and rhythm as well as several other intangibles are what gives a song its flavor.