The first very short tip is about low frequency content. Obviously everyone wants a tight, well-defined low end, which is so powerful that you can feel it in your stomach, yet so clear that it’s never mask or overpower the rest of the spectrum.
To achieve this, our very best friend is the good old high-pass filter. This is not a secret, but we have to be careful with it, or else we can easily kill our sub power, left with a bass shy, thin sounding mix. On the other hand, if we don’t use enough of it, we might end up with boomy bass spectrum, nasty rumbling dialogue, eating up our precious headroom. Neither is good for us, so we have to be cruel and soft at the same time.
Use a 18–24dB/octave high-pass to filter out the junk, the unnecessary rumbling, and use another one, preferably with a gentle 6dB/octave slope to reduce the lower part of the sound.
It may sound strange, but with this technique, you’ll have a very natural sounding low-end, which remains powerful, but very controlled. The added benefit is that you can automate it easily, so whenever you need a little less or more cut, just move the filter lower or higher and you’re done.
Alternatively if you don’t have such a clever eq plugin that can provide two high-pass filters, use one high-pass to filter out the super-lows, and use a low shelf to execute the necessary low cut.