Ask HN: How to be better at writing internal proposals and design docs?

[throwaway24124]

I'm hitting a point in my career as a software engineer where I'm spending a lot more of my time writing internal design docs & technical proposals within my company. Writing (especially technical writing) is a skill that I've under-invested in for the past few years.

How have you improved your technical writing, and also what are some of the best examples of clear, concise technical proposals?