Track selection is paramount, and depending on the genre, I think the actual mix points are the next most key phrase, the perfect first beat on first beat drop, all the changes happening together, track A dropping out right as track B breaks down/really drops into the meat of the tune. Nothing worse than missing the drop point and track A ending while track B is still in the intro and not full enough to support the dance floor (back in the days of records so no looping the outro )
Pete Gordon - Deep and Low

Slower tempo but still with balls, deephouse, slow-mo, futurehouse, nudeep, indie, nudisco, hints of progressive, whatever the fuck you want to call it, just good shit! Get on it