Paul Graham

An essay begins with a question. You notice a door that’s ajar, and you open it and walk in to see what’s inside.
Surprise the reader by telling them something they always knew deep inside but didn’t bother to do the work to make it conscious.
Collect surprises. It’s a trainable skill. The more anomalies you’ve seen, the more easily you’ll notice new ones.
Pay attention to things you’re not supposed to. If you’re curious about something, trust your instincts. Don’t believe what you’re supposed to.
Expressing ideas helps to form them. In a real essay you’re thinking out loud.
Writing something that other people will read forces you to think well.
Don’t plan. From paragraph to paragraph let the ideas take their course. Real thought is full of false starts. An essay is a cleaned-up train of thought.
Of all the places to go next, choose the most interesting.
Aim for maximum surprise – things you didn’t know that contradict things you thought you knew. What surprises you?
Ask ‘why’ about things that feel off. That’s where fruitful material is.
Read it out loud and fix everything that doesn’t sound like conversation.
Ask reviewers for two things: which parts bore them, and which seem unconvincing.
Cut the boring bits.
Make unconvincing bits more clear, or change what you’re saying if you’re wrong.

George Orwell

Bad writing has two qualities: staleness of imagery and lack of precision.
Tabulate your thoughts in precise and detailed ways.
Prefer concrete to the abstract.
The great enemy of clear language is insincerity.
There is no such thing as keeping out of politics. All issues are political issues.
Grammar is of no importance, so long as the meaning is clear.
If you simplify your language, you are freed from the orthodoxy.
Put off using words and get the meaning clear through pictures and sensations.
Then choose – not simply accept – words that will conver the meaning.
Pick words for the sake of their meaning and invent images to make the meaning clearer.
Use arresting imagery, simple verbs, and short words.
Never use a metaphor, simile, or other figure of speech which you are used to seeing in print.
Never use a long word where a short one will do.
If it is possible to cut a word out, always cut it out.
Never use the passive where you can use the active.
Never use a foreign phrase, a scientific word, or a jargon word if you can think of an everyday English equivalent.
Break any of these rules sooner than say anything outright barbarous.
In every sentence ask yourself: what am I trying to say? What words will express it? What image will make it clearer? Is this image fresh enough to have an effect? Could I put it more shortly? Have I said anything that is avoidably ugly?

List as many arguments as you can. When you can’t anymore, you’ve probably listed most of your cached thoughts. Don’t use these.
When in doubt, go for maximum surprise.
Concrete is better than abstract.
If it is possible to cut a word out, always cut it out.
Don’t hedge. Decide what you want to say and say it as vigorously as possible, without apology and in plain words.
Avoid pat expressions. They are no creation of yours but pieces of common thought floating in the community soup.
Choose words that are dressy instead of plain, specific instead of general, loud instead of soft. E.g. in place of “her heart beat,” we may write, “her heart pounded, throbbed, fluttered, danced.”
However, it should not be supposed that the fancy word is always better. Often it is as well to write “Her heart beat” or “It was hot” if that is all it did or all it was.
The meaning of a word is the sum of the contexts in which it occurs. When we hear a word, we hear with it an echo of all the situations in which we have heard it before. E.g. when you hear “mother” you probably think of home, safety, love, food.
Words like “mother” are loaded with associations that are hard to indicate in a straightforward definition.
Avoid words of such general meaning that in a particular sentence they mean nothing (e.g. “nice”).
In particular, avoid nouns of general meaning (e.g. circumstances, cases, instances, aspects, factors, relationships, attitudes, eventualities).