I've created archetypes/post.md containing some fields. Most of them are just there to remind me that I should fill them in:

---
zyzio: url
hg:
  - foo
aliases:
  - bar
cover_img: url
social_img: url

---

After hugo new post/foo.md, it turned out that hugo unhelpfully sorted all of the fields:

---
aliases:
- bar
cover_img: url
date: 2014-08-29T23:18:10+01:00
hg:
- foo
social_img: url
title: foo
zyzio: url

---

Not really helpful :(