Polo is a fast and furious subject to photograph, all the usual sports photography challenges apply:
Fast movement, rapid exposure changes, awareness of clean backgrounds, accurate focus, capture peak of the action, anticipation, get the ball in the frame, composition, good light…
Try and get all these things together and add healthy touch of luck and your on your way. Obviously spending time on a subject lets you ‘read’ the sport better but don’t let unfamiliarity with a sport put you off having a go at getting some pictures.
You don’t just have to fill the frame, try shooting a little wider to go for more of an ‘arty’ shot, and don’t forget about the prep work going on behind the scenes with the grooms getting the horses ready, feeding them and putting the saddles on, there are plenty of documentary shots to be had.