In "pilot waters", I keep a
handheld ready, and keep it on it it's a trafficed area.
I also keep a horn, or on smaller boats, a whistle around my neck handy, because the other guy may not have
radio (trouble is, he probably won't understand what "two whistles" means either. If, god forbid, you end up in a collision, it will go better for you if you tried both whistle and
vhf, and other guy didn't.
Ultimately, in clear weather, the easiest way to signal the other guy is by making a sharp change in your own course. But you're not always free to make such an alteration.
Frequently i have to motor out in a narrow, unmarked channel, where the only water deep enough for my near-7 foot draft, is on the port or "wrong" side near the channel mouth. Incoming boats, who draw less and don't know or care that there's a shoal on the "right" side, can get confused by this. I try to time it that I don't meet them at that spot, but sometimes can't be avoided. I wish they were all on the
radio--most aren't.
Once out on open water, I don't monitor
radio unless vis is poor, or conditions are bad (someone might need assistance or info) or there's visible traffic.
All this in a very maneuverable, fast 26-foot sloop.