for mixing really busy things, I like to assign stuff its own vowel formant and think of it in terms of 20-60, 60-120, 120-250, 250-500, 500-1k, 1k-2k, 2k-4k, 4k-8k, & 8k-16k Hz and try and fit each piece into one of those. Normally the kick and bass all kinda bleed into 20-250, but Eq'ing other elements aggressively to fit into those other bandwidths really helps clean up my mix. Then I can think of each element's stereo spread and level balance as pink noise