At my place:
Rotating beacon - ON whenever engine is running or start is imminent
Navigation lights - ON when deemed necessary or legally required, low vis and night mostly.
Strobe lights - ON when entering active runway.
Then we've got some BE76 that doesn't have any rotating beacons, so we have to use or strobe lights as anti-collision. Acceptable under FAR Part 91, but you feel a bit silly at night flashing everyone else in their face.