Post Production Video and Film Sound

GIGO -> garbage in, garbage out
All this presupposes that there is no better way to solve a sound problem than by getting it right in the first place.

Make the Voice Stand Out
Our ears hear a highly complex and interconnected audio tapestry. Cutting and boosting the different audio tracks at strategic points in the sound spectrum is the main trick. EQ is capable of taking certain frequencies and either boosting them or padding them down so they're not as prominent. Sometimes, a track or frequency will sound louder just because you decrease a frequency from yet another track. So it's interactive -- you have to listen, try things, and listen again.

The human voice is in the low to mid ranges, and it can be boosted for enhancement. Hiss is high end stuff. Cut high end frequencies out and maybe the hiss will go away. But so will some of the life and brilliance of the sound. Therein lies the rub. A good mixing board can be used to 'notch' out a particular frequency and a good set of ears, of course, is needed to determine when it is helping and when it is detracting from the "sound quality."

The goal is for all your elements to have their own sonic space, which is done mainly with frequency -- ideally each element can have it's own part of the frequency spectrum.

Otherwise, sounds that fluctuate wildly in level might need to be compressed -- however -- too much compression makes things sound unnatural. Bumps cracks and other audio blemishes need to be removed. Most of the sound program I've seen have Equalization and compression.