Leaving an itinerary with someone is a great idea. If you don't have anyone to leave it with, then leave one in an easy to find place so that if someone walked into your home it would be readily noticed. Middle of table with nothing else on table, middle of made bed, taped to front of tv or computer screen. Even if you do leave a copy with someone, a backup in in your home probably won't hurt.

I have a whistle attached to my shoulder strap. My thought is if I fall and hurt myself so I can't move, I can probably reach it. It's better than having to dig through a pack with a broken wrist (common fall injury). Three long blasts is a universal SOS signal, and one can last much longer blowing a whistle than yelling for help.