Write as though you were chatting with an intelligent friend who may not be familiar with the specifics of what you are covering. Never talk down to the reader. Use short sentences. Be careful with your humor, particularly sarcasm and irony. Printed matter has the same limitations as electronic mail.
Intentions are easily misread and can be offensive.
Many readers have English as a second language and are not immersed in American culture and topical matters. If you realize you cannot meet a deadline, please let your editor know as soon as possible. It is helpful to have a technically competent colleague look over your work, especially any code, before submitting it.