( . . read the question first Grazie - seeesh! totally re-edited this)
Firstly I search a common flash of light. This gets me to within about 2 secs. Then for a sounds for all the cams THEN I hone in on the same flash of light. ( yeah just got one!)
Peter's "phasing" method is good. Combine this with Loop editing, meaning put the section on loop play back and listen for the phasing. Use the keypad buttons to "shift" while listening/playing back - yeah?
If you can, use a clapper/slate or camera flash. That would be extremely easy to sync. A flash from a camera would not work for sound-only devices of course.
On the smaller off-broadway projects we've done, I've used a small "clicker" that's one of those little metal frogs. It's so loud, it works great. It's so high pitched, it doesn't really bother anyone. On one or two occasions, I've even used it in the middle of a live shot. (urp!)
We used to use a camera flash to synch multiple cameras, but it's so fast that often it would fall between frames and be missed by one or more cameras.
Now we use the old-fashioned method of the talent clapping, or if they're playing an instrument, hitting a sharp sound so we can synch the audio recorder too.
Best method of getting it spot on is to roughly align then zoom right in and get the audio waveforms to match up.
Oh, you have to disable "Quantise to Frames" in the option drop-down, too.