Listen to the whole track before ever DJing it. That may seem self-evident, but given the time pressures of modern living, and the urgency need we can feel to build up a great collection of music as quickly as possible, it’s easy to get half-way through a track, go: “This is a great version! Next!” and add it for later DJing.
Which, I suspect, is why I’ve seen dance floors cleared by distinctly non-dancer-friendly drum solos in otherwise amazing tracks (here’s a classic from the end of Bob Crosby’s amazing Smokey Mary, where Ray Bauduc seemed to get a little bit carried away)
Probably the most common issue is when there’s a lot of rapturous applause at the end – a little is fine, but too much, and it needs fading off.
Nothing I’ve heard quite beats this one though, which comes from a live recording of Duke Ellington’s Fickle Fling, presumably from a radio broadcast. Admittedly, it’d be hilarious to hear this happen out on the dance-floor, but I’m not sure I’d want to be sitting behind the DJ desk at the time.
So … yeah. It may take a bit more time, but it’s worth it, especially as a little judicious editing can make the difference between a track you can’t play, and an absolute killer.