Use a small diaphragm (1/2 inch or smaller) mic on Cameras.
Omni to pick up the entire room, directional to isolate sound source, shotgun or hyper cardioid to mic from a distance and isolate the sound source.
Condenser mics usually require power.
Lavaliere mics work well on the chest.
UHS is preferable to VHS wireless receivers. Either is better than FM.
You can use a small mixing board to record to sound sources into the camera or you can record the sources to the L and R tracks and set levels in FCP.
Always listen with headphones as you record. A computer in the room that you can’t hear could be all that the camera picks up.
When recording to analog media (cassette tape) try and record it loud as you can. This eliminates hiss. Over saturating an analog tape sounds like distortion.
When recording to digital (DV tape) leave some headroom. Over saturating a digital recording is a horrible sound.
XLR connectors are better sound quality that mini jacks.
Some words about mix down.
You can make someone sound louder without raising the volume by using a compressor. TV commercials use this technique.
Reverb/delay adds depth. Reverb/delay sounds different in headphones. After listening to reverb/delay for a few minutes you may want to add more. Don’t.
When you eq, it’s better to remove a bad frequency than to try and boost a good one. Try this approach when trying to make to voices balance.
It’s a good idea to record backup audio from a different source.
Know how many tracks you can record on and make a plan before the shoot.