I concur with the doubts about Wilderness Protocol.

Having the repeaters in the vicinity correctly pre-programmed in the radio, having a supplementary higher-gain antenna (I carry an extendable 5/8 wave whip which is better than the stock rubber dummy load), having fresh batteries and understanding effects of terrain are most of the effective things to remember.

Some hams still learn Morse code which could be useful aside from radio. Maybe the Boy Scouts still have a merit badge for Morse? Flashing light or whistle signals can be used for signalling something beyond SOS (meaning "I'm here" in the context) if someone in the rescue party can read it. SAR folks are often hams too. Some of them can read code so it's not as long a shot as it might seem.(My ability to send/receive code is part of the personal info I have on my trip plans I leave with my wife when I go hiking.)

de NW0U

A very long hike on the Continental Divide aided by ham radio story here (no daring rescue though) -
http://estes.on-line.com/rmnp/reports/HighDivide.html (The email address given in the story is no longer valid. The site moderator doesn't respond to emails so it can't be changed.)