Dragon flies usually like to be on a high point so they can depart in any direction. You might notice how many of these are at the peak of the stem they have chosen to land on. I'm willing to bet it was also the highest one for about one metre in any direction.
One way to shoot them is to see a spot like that which is being used. Stay away a couple of yards and see if they are returning to it. If so, move to it slowly and stand still while they go out and hunt. They will come back to you.
Of course, I did screw up one time and was at a slightly high angle and the dragonfly decided my monopod and camera was a better perch. I hate it when that happens.