Once upon a time, I always thought like an arranger when I arranged, like a composer when I composed. Effective voicings. Timbre, texture, form, phrasing.
I still think about all of those things, of course. But I prioritize thinking like the performer.
Would I enjoy singing this? Would this read well? Would I want to come back and sing it again next week? Is the harmony more important than the voice leading? (In other words, is it weird to sing?)
When I’m writing for big band and vocal group (as I am now), is there enough for the band? (I’ve been guilty of writing bland band parts because I’ve been too focused on the vocal writing.
I think that if I’m always thinking like the performer, I’m going to write things that feel good to perform, and that will lead to more and better performances.