Just another vote in favour of shouting. It gets everyone's attention even if the actual words might not be recognised.
But also a point about the use of anticollision lights. Of course they are a good idea: anything to increase awareness of others that this aircraft is about to start engines. Indeed, it is SOP for most commercial operations that ground crew will not approach the aircraft whilst the anti-colls are on, even if the engines are stopped (see story below).
However, I am stunned at how many times I see people who have just refuelled and are parked right next to the pumps go through their prestart checks and switch on the wing strobes (not selectable apart from the tail beacon on some Cherokees, for example.) It seems like a very bad idea to me to have a high ampage charge of electricity going off not three feet away from a fuel pump. Any sparks or vapour leakage and the world will get quite warm. Leave them off, shout 'Clear prop' and switch them on once you have moved away from the pumps.
Reference anti colls:
There is a story, maybe true, of a trip by HRH Prince Charles to an oil rig in the North Sea. I understand that is common practice for helicopters there to leave rotors running while they unload, and the clue to the deck crew that it is safe to approach the aircraft is the switching off of the anti-collision beacon.
Anyway, the day arrived, everyone was keen to ensure the visit of HRH went smoothly, and the Deck Landing Officer (or whatever he's called) was anxious that HRH should not be delayed exiting the aircraft. The helicopter arrived, and sat on the pad with engines winding down, but the anticoll still on. After trying to get the attention of the pilot, the exasperated deck officer eventually called up on the rig frequency:
"Turn your F***ing beacon off, you F***wit so I can approach the F***ing aircraft!!"
At which point the pilot removed his helmet to reveal: HRH
