Dragon watching is similar in many ways to birdwatching. With odonates there are fieldmarks that help you identify which genus the dragon is and which species, males and females are often different colors, and habitat has a lot to do with where you find certain species. These three things are also true with birding.
The field markings on this particular skimmer dragonfly are very telling. This dragonfly is almost all black except for the small yellow dot on the back of the abdomen and the bright white face. So if you put the field marks together you will get a dot-tailed whiteface which is what this dragonfly is called. Another similarity between dragons and birds is that they are often very seasonal. The dot-tailed whiteface is a dragonfly that you often see very early in the year, usually starting in May here in Minnesota, but you do not see many of them come August. One glaring difference between birds and odonates is that it does not really work to put up dragon feeders.