Here's another little tip: Remember those clapper things used in the movies (They're called slates) … They provide both an audio mark (the sharp sound) and video mark which, when you use a editing program (sony movie studio/adobe premier elements come to mind), will be quite visible both on your camera track and the audio track.
One of the better keys is that by using something like the zoom mic, you can place it (or even hide it) on the set or on the person (Or even mic each person).
Frankly, while there is the task of synching the audio, ususally a product like the zoom will give you much better sound than an onboard mic setting will.
Oh, and if you don't have a slate 🙂 with which to do the clapper, often a flash or even a single clap will take a minute or two off your task of synching. It is also good to make sure, especially on longer videos, that you maintain your sync.
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