From the very wonderful Brain Pickings:

In 1932-1933, while working on what would become his first published novel, Tropic of Cancer, Miller devised and adhered to a stringent daily routine to propel his writing. Among it was this list of eleven commandments, found in Henry Miller on Writing — a fine addition to these 9 essential books on reading and writing, part of this year’s resolution to read more and write better.

COMMANDMENTS

Work on one thing at a time until finished.
Start no more new books, add no more new material to ‘Black Spring.’
Don’t be nervous. Work calmly, joyously, recklessly on whatever is in hand.
Work according to Program and not according to mood. Stop at the appointed time!
When you can’t create you can work.
Cement a little every day, rather than add new fertilizers.
Keep human! See people, go places, drink if you feel like it.
Don’t be a draught-horse! Work with pleasure only.
Discard the Program when you feel like it—but go back to it next day. Concentrate. Narrow down. Exclude.
Forget the books you want to write. Think only of the book you are writing.
Write first and always. Painting, music, friends, cinema, all these come afterwards.

Under a part titled Daily Program, his routine also featured the following wonderful blueprint for productivity, inspiration, and mental health:

MORNINGS:
If groggy, type notes and allocate, as stimulus.

If in fine fettle, write.

AFTERNOONS:

Work of section in hand, following plan of section scrupulously. No intrusions, no diversions. Write to finish one section at a time, for good and all.

EVENINGS:

See friends. Read in cafés.

Explore unfamiliar sections — on foot if wet, on bicycle if dry.

Write, if in mood, but only on Minor program.

Paint if empty or tired.

Make Notes. Make Charts, Plans. Make corrections of MS.

Note: Allow sufficient time during daylight to make an occasional visit to museums or an occasional sketch or an occasional bike ride. Sketch in cafés and trains and streets. Cut the movies! Library for references once a week.

For more of Miller’s obsessive recipes for creative rigor, dig into Henry Miller on Writing.