What should pilots state initially when telephoning a weather briefing facility for preflight weather information?
It's in the AIM 5-1-1(f):

When requesting a preflight briefing, identify yourself as a pilot and
provide the following:

Type of flight planned; e.g., VFR or IFR.
Aircraft’s number or pilot’s name.
Aircraft type.
Departure Airport.
Route of flight.
Destination.
Flight altitude(s).
ETD and ETE


Personally, I've never given or been asked for the aircraft type (although I have it on my LMFS profile so they should have it), but the other items come up. My typical request is something like this:

This is N12345, I'd like a standard briefing for a VFR flight from
KMDQ to KLOU at 5500', ETD at 1600Z, ETE 2h15