This principle is better stated in another thread around here somewhere but, paraphrased: Think of your entire mix as a story with an introduction, conflict, resolution, and ending. Different tracks give different vibes and create different atmospheres and you can use that to your advantage to mold the storyline to your liking. So instead of thinking “now I want a tech-house tune, now I want something more minimal, now a tempo change, etc.” think more along the lines of “this is the part where boy-meets-girl, this is the part where girl-meets-other-boy, this is the part where other-boy turns out to be not-a-boy, etc.”
At least it works for me to keep things flowing.
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