Photograph something once a day, week, or year.
If you photograph something once a day for a week or two, you'll learn more than you think you will about light.
Longer projects are possible, too.
Nicholas Nixon has been photographing his wife, and her sisters, annually, for over thirty years.
These two families have been documenting themselves for many years:
Time Goldberg familiy
Here's another family series.
You can start an annual photography project.
The subject can be family, or something else, such as a garden.
Duane Michals did a seasonal project.
He photographed his garden each season, and hand colored the B&W prints.