From AC 120-74A...
b. Exterior Lights. To the extent possible and consistent with aircraft equipage, operating
limitations, and flightcrew procedures, pilots should illuminate exterior lights as follows:
(1) Engines Running. Turn on the rotating beacon whenever an engine is running.
(2) Taxiing. Prior to commencing taxi, turn on navigation, position, anti-collision,
and logo lights, if available. To signal intent to other pilots, consider turning on the taxi light
when the aircraft is moving or intending to move on the ground, and turning it off when stopped,
yielding, or as a consideration to other pilots or ground personnel. Strobe lights should not be
illuminated during taxi if they will adversely affect the vision of other pilots or ground personnel.
(3) Crossing a Runway. All exterior lights should be illuminated when crossing a
runway.
CAUTION: Flightcrews should consider any adverse effects to safety that
illuminating the forward facing lights will have on the vision of other pilots
or ground personnel during runway crossings.
(4) Entering the departure runway for takeoff or “position and hold.” When
entering a runway either for takeoff, or when taxiing into “position and hold,” flightcrews
should make their aircraft more conspicuous to aircraft on final behind them and to ATC
by turning on lights (except for landing lights) that highlight the aircraft’s silhouette.
Strobe lights should not be illuminated if they will adversely affect the vision of other pilots.
(5) Takeoff. Turn on landing lights when takeoff clearance is received, or when
commencing takeoff roll at an airport without an operating control tower.
NOTE: The SOP of turning on landing lights when takeoff clearance is
received is a signal to other pilots, ATC, and ground personnel that the
aircraft is moving down the runway for takeoff.
for what it's worth. And before you ask...yes, I am bored.
