When I'm writing a song, I tend to just noodle around with chords until I find a progression which sounds right.

I know there is a more logical way of doing this, understanding key signatures and the roman numeral chord progression system... can any of you recommend me a book that covers these topics?

MattyJam said:

The part in bold is critical, but I encourage you to also learn a variety of scale patterns. After, default back to what you were doing, which is what feels right.

Hey Matty - here is a starting point for you, but in no means "set in stone"

First, you can pick up a good theory book from any book store like Barnes & Noble. They all say the same thing, so find one that seems to be the most clear to you as you look through it.

Until then, here is a simple formula that will get you started, regardless of key.

Pick any note as a root and write out the notes for the major scale.

The scale pattern is

Root - Whole Step - Whole Step - Half Step - Whole Step - Whole Step - Whole Step - Half Step

For C major, that would be C - D - E - F - G - A - B - C

Now for the formula...

1 - Major (or Major 7th)
2 - Minor (minor 7th)
3 - Minor (minor 7th)
4 - Major (Major 7th)
5 - Dominant (7th)
6 - Minor (Minor 7th)
7 - Half Diminished (Minor 7 flat 5)

In C - Cmaj7, Dmin7, Emin7,Fmaj7, G7, Amin7, Bmin7b5

This formula works in every key, you just need to be able to figure the notes out from your major scale.

Next, work on putting the chords together is ways that sound good to you. Here are a few common progressions...

1 - 6 - 4 - 5
C - Am - F - G7

1 - 4 - 5
C - F - G7

3 - 6 - 2 5 - 1
Em - Am - Dm G7 - C

A theory book will help you move from this into more complex structures like using diminished chords as passing chords, slash chords to add bassline movement between chords, etc.

And as always, the best way to learn is transcribe, transcribe, transcribe.

But don't just transcribe the music, transcribe the lyrics too. Break down the lines, rhyming conventions, couplets, etc. Take some Dylan or Joni tunes and tear them apart. It'll be time well spent.

As always, good luck!