The first thing I do when working on a new song is to map out the structure. I mark where the verses and choruses are so I can more easily navigate through the song. The second thing I do is figure out the chord progression. Depending on the song, that can take a while. To save myself a lot of time (assuming the song writer hasn’t simply told me the chord progression) I make use of the following free tool called Chordata.
The display may look a little complex in places but I focus on the section at the bottom with the chords in the colored rectangles. I simply load an .mp3 or a .wav file into the program, press play and write down the cords. I find it works best if I give it an individual track, like a piano or a guitar so that the chords this program has to detect are as clear as possible. I also tend to give it a single verse or chorus at a time. Navigation within the program is easier that way and It’s also easier to keep track of where I am in the song.
This program has it’s quirks, but does a fairly good job of chord detection and saves me a lot of time. It may make the occasional mistake but generally it’s accurate enough that I keep using it. Check it out: