For me, something will come in my head and I'll either end up calling my cell phone to record it, or I'll just pick my guitar up and see what comes out. Sometimes it sucks, sometimes it doesn't. So there's really no set method behind it. ↗
I've played every instrument you could possibly think of for 10 minutes. So I'm mediocre at everything. I can play drums, guitar, piano, violin, saxophone, clarinet, flute... Just not well. ↗