Streamingmedia.com recently created a great article detailing best practices in Live Audio and Mixing. We're going to break down some of the finer points of this article.
Fading and Limiting Compression
If you are editing with crisp, clean, strong audio- the person who recorded it has a solid mastery over the input trim on the microphone they're using.
If the mixer you're using to record has the ability to record a solo channel, use that channel and have subjects speak at "program level" as you adjust the input trim.
Adjust Audio Levels on a Mixer Based on Location
For those recording sports, set the level at above a conversational tone. There's a major difference from "hello, hello, 1, 2, 3" being said into a microphone as a test- and the announcer yelling into the microphone in the heat of the moment.
For live events like sports, sound mixers must be hyper aware of the peaking audio levels.
Set Your Limiter and Compressor
Limiters and compressors keep the loudest part of your audio from hitting the digital zero. This is where the sound clip creates a "square wave", not a "Smooth sine wave". In most cases, this will sound awful for users.
Clipping is to be avoided as much as possible. However, I’ve heard clipping audio even when the faders on the mixer were not up that high and the output of the mixer was going into a compressor. The operator was confused because the output level was being properly handled—it was low, not in the red—yet it still sounded bad.streamingmedia.com
Another major factor to consider when mixing live audio, is that clipping can occur whenever any frequency hits maximum level. Clipping LEDs don't indicate which frequency is clipping.
Wind noise can be an animal unto itself. How do they get such clean audio in such windy situations in the movies? They redub everything. But in a live stream, we don’t have that luxury. So those audience mics in the stands at the outdoor game could become nothing but noise as the winds of a cool front move in. Or a poorly placed room mic just might be directly under the HVAC vent, and thus it becomes unusable every time the air conditioner kicks on. Or the lav mic is placed high on the chest of a noisy breather, etc.streamingmedia.com