Key Points:

Skin tone can change and should be reassessed at every visit.
Recently tanned skin should not be treated. The skin must return to baseline first.
If there is post-inflammatory hyperpigmentation, treat that area more conservatively.
If there is self-tanner, do not treat until it is removed.
When in doubt, move more conservative or delay treatment.
Wavelength selection is based on how energy moves through the skin, not preference.