Songwriting, arranging, recording, and the rhythm section. You know, the stuff that isn't guitars.
Often times, as musician/songwriters, we begin the songwriting process with one single part. A riff, a progression, a melody, whatever you want to call it, it's the first thing that pops into our head, and we like it, so we start to build a song around it. It's a very natural, very straightforward way to write a song. However, sometimes once we have our original melody, our countermelody, our rhythm parts, our bass lines, and everything else worked out, we can listen to what we've created and ...