My trick to start emails is to add To and Cc last, when I'm happy with the email.

If I add them first, I worry that I'll click send by mistake halfway through my draft (and a secondary worry is that the draft will be full of inappropriate stuff and curse words, which I never add even to drafts, so it's not a rational thought). If I add the recipients first, it also feels like they sit there looking at me expectantly as I write, which makes it harder.

An email not addressed to anyone, but of course with the recipients in mind to adapt the content, makes it easier for me to treat the first version as a draft.

Sleeping on non-urgent emails sounds like an excellent idea, because your view of the issue may change.