this should be in the mixing board but uh
the biggest thing for me is that i want the low end to be significantly louder than the high end of the kick. typically what i'll do if i'm not using one of my own samples is i'll boost the low end of the kick first, and then slam it into a limiter to bring the transient back up (bc when u boost the low end of a kick it makes the waveform look like a / )
then u just add a short sidechain to everything to let the transient in and sidechain your sub to the low end of your kick and you're done