Q: So I've learned that in order to figure out the next part of a song, I should listen to it and imagine what comes next, but what if I have a part of a song and I want to figure out what comes before it, like to make an intro
A: i really have no idea how to do that, but it still has to be done sometimes. here are some tricks you might want to try. try continuing forward without the intro for now. then, keep writing until it winds back around to the part you have (most songs tend to do that, unless it's one of those 1-way songs, which is possible). When it comes back around, check out what happens just before it comes back around. the solution can sometimes be found there. another trick is to try doing almost nothing