I recently read Ernest Hemingway on Writing, a collection of advice gathered from his letters and books, and I’ve paraphrased what I felt were the most important points.
This first list is general advice on being a writer and what makes good writing:
Write only about what you really know.
If you use real people, do not change them at all.
When you invent people, make them real. Characters are people, not symbols.
Be concise. Do not be afraid of omitting and cutting.
Do not force your ideas into the story.
Writers are individuals; they are not members of groups.
Be perceptive and write exactly what you observe and feel.
You can write about something without ever mentioning it.
Avoid the epic and write on a smaller scale.
Do not write what someone else has already written unless you can do it better.
The second list is about the writing process:
Do not read before you start writing each day.
Stop writing when you know what you will write next.
Do not think about the story once you stop writing. (You may read at night to stop you thinking about your own story. Whisky and sex also work.)