A good way to work on something is to work on something else. Obviously, we've all heard this before as a matter of incubation in the creative process. While it is in fact incubation, it is also a matter of shuffling the sequence of tasks involved in creating a final product.
What I like to do in music is to work on the visual art, and perhaps listen to some music that may inform the music that I'm composing.
On the album I'm currently working on, Music For Places V, the album art started to look like an ECM album, and put me in that head space.
It's interesting to observe what happens when you take a circuitous path in creativity. So if you apply the idea that you can work on something else, you'd always be working on something else. In my experience, even if you keep diverting your attention away, it is nourishing the original project, and may be giving you new ideas for other projects.
The way we typically like to work is to sequence the process in a linear fashion--as if we were organizing it on a Gantt chart. While this is important--and I have in fact used them--anything that is not deadline-driven can meander around, and we should take advantage of that more roaming style to scatter the ideas around.