If you're dealing with a project with a lot of low frequency information, balance is going to be one of your biggest battles during mix down.
Kicks, subs, fundamentals of the rhythm section, bass and other tracks all occupy the low end of the spectrum. If arranged in such a way where these low frequencies are offset from one another, mixing becomes a lot easier. However, this is seldom the case. More often than not, a combination of these instruments may happen at the same time. This can provide difficult challenges during the mixing stage and decisions must be carefully considered.
It is a common misconception that a bottom heavy song must have a big kick and a heavy bass. This can be a deadly combination when thinking about phase and can sound uncontrolled. As well as sounding uncontrolled, phase cancellation may occur, therefore, keeping it simple and sharing the spectrum is the best approach to a clean and prominent low end.
To further control low frequencies, try sidechain compression. This allows the input of a kick to trigger a compressor on another track such as the bass. Whenever the kick drum is triggered the bass will 'duck' the kick and once the kick has passed, the compressor will release the bass repleting the signal. You may apply the same technique to other instruments occupying the same frequency band if standard EQ and compression don't correct the issue.