I have been taking tango pictures intensively for more than 2 years now. Most of that time I’ve been using a Canon 350D with a number of lenses. What’s special about tango pictures? Most importantly, the tango events are in the evening/night with minimal lighting. I avoid using a flash, since it’s unpleasant for the dancers and because the pictures have very sharp and ugly lighting. Another thing is that I don’t use a tripod. I can’t tell the dancers where to move or to stand still, so I go with the flow. The fact that they move also means I need a shutter speed of 1/15s at the slowest; 1/20s is better and 1/40s is comfortable.
All these tips come down to the same: get the fastest shutter times possible while keeping the picture quality acceptable.
#1: take the highest ISO your camera can afford
If you can use sensitivity ISO 800 instead of ISO 100, you’ll win 3 stops. This is the difference between a picture at 1/40 sec (sharp) and 1/5 sec (blurry), certainly with moving targets (and tango dancers do move). Of course there is a trade-off: you loose colour detail.
This is the main reason why you’ll need a camera with a decent sensor, or in other words, an dSLR instead of a regular point-and-shoot camera. Even my 350D gets colour defects at ISO800. When they’re too bad, I tend to convert the pictures to black-and-white or somewhere halfway (by decreasing the saturation).
The camera I’m drooling over now, the Canon 5D Mk II, can take decent pictures at ISO 3200. That’s another 2 stops faster.