The most common mistake is not choosing the wrong device. It is using a good one enthusiastically for nine days, then never again.
Attach it to something you already do
Do not schedule a session. Attach it. Ten minutes while the coffee brews. Ten minutes with the podcast you were going to listen to anyway. Ten minutes before bed, while you read.
Anything that lives where you already sit removes the setup friction, and setup friction is what kills most routines long before boredom does.
Keep sessions short
Longer is not better. The photobiomodulation literature repeatedly describes a biphasic dose response: a window where the dose appears useful, above and below which the effect falls away.
Doubling your session time can move you past that window rather than deeper into it. Follow the time and distance in your device manual — the two numbers belong together, because changing one changes the dose.
Pick one target and stay with it
Chasing a different body part every evening makes it impossible to tell whether anything is happening at all. Choose the thing that actually bothers you, and give it several weeks before you form an opinion.
Short and regular beats long and occasional. Every time.
Track it, loosely
A note on your phone once a week is enough. Not a spreadsheet, not a daily score. You are watching for a slow trend across a month or two, and daily verdicts will only tell you what kind of day you had.
Effects vary between people, and some published results are modest. PHŌRMA devices are wellness products, not medical devices, and nothing here is medical advice. If you are pregnant, take photosensitising medication, or have an eye or skin condition, speak to a doctor first.