I use my phone to record, and go for a walk in the woods and hum what I've written so far. I always end up spontaneously adding something new, or varying the rhythms, or putting in a key change, without really thinking about it as I go. There's something about walking and getting away from the paper that seems to loosen up my brain, and then I have a record on my phone that I can go back through when I'm home again to remember what I came up with and write down the best parts. Driving seems to work well too. Something about being in motion. There is a need to fill the aural space with sound, and the brain obliges. (: But for me, the most important is a way to record, so that I can just hum, without trying to write it down at the same time. It seems to free up my brain to let the music out.