How do you determine the basic accompaniment chords to a simple song?

Question

Assuming you know the key of the song for what your playing, what are the 3 principle chords you should try to use to build a basic structure for the song?

Answer 1

Melody notes like to live in chord tones. Your melody is likely to be the root, third or fifth of a chord, so try to test out those combinations and see if you find one that is pleasing to you. Of course, not every note is going to be a chord tone, so you need to use your ear and the context to figure out which notes are and aren't emphasized harmonically.

Once you figure that out, you can start with a simple progression of tonic, subdominant, dominant and back to tonic. An example of this would be I-IV-V-I, or in C-major, C, F and G major chords. However if you want to make it more exciting, you can feel free to use all of the diatonic chords available to you in the scale and if you want to be really adventurous, start working with other harmonic devices which a teacher can show you!

Answer 2

As you play the melody start with the root or one chord if it sounds right. Then if or when that chord doesn't sound appropriate change to the IV or V chord in the original key to see hear if it sounds correct. Continue this process through out the song. If you cannot determine the chord for a section of the song try using a ii, iii or vi minor chord and listen to hear if it sounds appropriate. If part of the song doesn't sound right using the above methods try using a V/V or V/II chord to see if it works. If that fails try building a triadic chord from the melody note in the song of that measure to hear if that fits it.