Use type size legible to those with poor visual acuity.
Avoid overuse of bold or italic type.
Use short words and short sentences.
Use illustrations which put across a specific message.
Avoid unnecessary words.
Be personal and avoid common use of the passive.
Use concepts and phrases that all readers will understand.
Avoid unnecessary capitals.
Follow rules of grammar and syntax.

Um ótimo guia para a escrita. Do Guardian.