Writing music is 90% intuition and emotion and 10% mathematics. You don't have to know the math side of it to be a great songwriter, that's for sure. But knowing the logic behind what chords go well together to express your emotions musically can make even an average guitar player a better writer and it can make a good songwriter great!
So you will probably find this lesson interesting if you are just getting into writing your own songs. And if you already write your own music you may still find this interesting as it might explain what it is you already know intuitively but never really understood.
Pick a key
You will have to start somewhere and you should start to learn what key and vocal range works best for your voice. For our example we will stick with the key of C to keep it simple.
If you read the lesson on finding the chords for a given scale, then you know that right off the bat you could choose to work with only chords built around the major triad. That means you would work with major and minor chords (don't bother with the diminished chord as it sounds a bit odd - unless you are a jazz fan).
The first thing you should know is that the most basic musical progression in rock music is 1-4-5. That means that you start and finish at the root chord (C) in this case and in between you play the 4th (F) and 5th (G) chords. Millions of dollars have been made using only three chords. It's amazing the infinite possibilities that exist using only those three chords.
Here is a chart that shows some very common chord progressions that you can use to start building songs right away.
Of course this chart only shows the chord progressions in the keys of C and D whereas you can use any of the twelve chromatic keys to vary these combinations. The thing to note is that the fifth (V) is almost always used as a turnaround point in songs because it heightens emotion and sets up melody to resolve or return back to the root.
These chords are all based the on the major triad of the first, third and fifth degrees of the scale (includes major and minor chords). But here is a twist for you.
When you start to write a song, remember that you don't have to rely solely on major or minor chords to create great chord progressions. You can substitute these with sevenths, ninths, or suspended chords to name a few. In fact that is what jazz guitarists do all the time. And you shouldn't rely on rules steadfastly only as a starting point from which to venture.
Here is an example of the kinds of substitutions that you can introduce to your songwriting.
And this is only introducing sevenths. You could add suspended chords or minor sevenths. The list is endless. But notice that the root notes remain constant in the sense that the 1-4-5 combinations are never too far away even though they may have been changed to sevenths or suspended chords.
If you remember only the 1-4-5 combination or the 1-6-4-5 combination and its derivatives you will be amazed at the possibilities that are at your fingertips when writing songs.