Use simple words.
Write small sentences.
Don’t use acronyms.
Use numbers:
“A lot of errors” → “42 errors"
"A small amount of users” → “5 users”
Lose useless adjectives:
“A very important message” → “An important message”
Order sections by most important first.
Keep it short.
Add as many appendices you want.
Discuss trade-offs in appendices.