For this session, we’ll concentrate on writing the key of G.
In this setting, the G chord is the most important. It’s the chord that is our ‘home base’. If you’ve ever heard of the 1, 4, 5 chords, this is what they would be referring to (when in the key of G):
The G (I) chord can lead to any chord. That’s the privilege of being the I chord because it’s the same as the key.
The C (IV) chord can lead to either G or D.
The D (V) tends to want to go back to G, but you can break this rule if you wish.
You can start and end the song on any of the chords, but much of the time you’ll want to start with G and 9.9 times out of 10 you’ll want to end on G.
There are already a zillion songs that use the G, C, and D chords. Many of them use these chords exclusively. The biggest reason, when it comes to the guitar, is that they are common open chords that are easy to play. Perfect for songwriting. Who really wants to write a song in C# on the guitar?
Do I feel limited about using just G, C, and D chords?
Well, you really shouldn’t feel limited. Like I’ve already said, there are a zillion songs out there that already use them. Besides, if you want to spice your song up a little more, just throw the relative minor chord in there during the bridge or something.
Am I afraid that I’ll just come up with the same old thing if I just use G, C, and D?
To be perfectly honest with you, anything you come up with will already have been done before. That’s music for you. There are only so many things you can play, so don’t worry if it sounds like something else. It’s going to happen. Look at it this way, if you take all blues songs, most of them are going to have an almost identical chord progression. Many country and rock and roll songs (especially old time) will share common chord progression, too. It’s just the nature of music.
Chords have a mind of their own in the context of a song. In any given key, certain chords are much better at following the previous chord than others. The harmonic properties of chord progressions lead our ears by a leash. For example, a song WANTS to end on the I chord. The song will feel incomplete or have a sense of ‘hanging’ if a song ends on any other chord.