Mixing Bass and Kick drum so they don't mask each other

A common mixing task is mixing your bass and kick drum so that they don't both live in the same frequency range and thus, mask each other out. You want them to work together like a key in a lock.  Here's a great video by Graham Cochrane showing a very common, basic technique to give each element its own space in the mix.  While this example is very subtle, the princible of creating mirror image EQs for bass and kick is a sound one, even when applied with less subtle cuts and boosts.

In addition it is also a good idea to choose which part should be prominant, and receive more emphasis in the song.  Typically, you emhasize whichever element (kick drum or bass) is more/most responsible for driving the song