It's a bit older, but Paolo Ciccone's Multi-camera synchronization tutorial is still useful:
"Sometimes you need to shoot with two or more cameras and that introduces the need to synchronize them. Some high-end cameras have genlock capability but what happens if you your cameras don’t have it or you work with a mix of different cameras? Slating is always a good idea but there is an easy way to have immediate synch in your NLE, this first tutorial shows you how."
Getting proper clapper can be awkward in many circumstances. Making a little movie with the Timecode filter in AE (for alternatives see AE Help), as Paolo recommends, is easy enough that you can get most camera people to shoot at a laptop playing this movie. And when using Premiere Pro, you can change the Timeline from timecode (video frames) to audio units (audio samples). This is a nice feature of Premiere because you can scrub to synchronize in 41,000 or 48,000 audio samples as opposed to 24 or 30 video samples.
I'm Not Bruce noted (along with other things good to remember) that Syncing Multipclips 1/100th of a Frame at a Time is possible in Final Cut, so better scrubbing is not just in Premiere Pro. In FCP, you can scrub in the audio Viewer with the Shift key down to help with precise tasks.