Dragonfly Identification
Not everyone will agree with me but I think the best way to learn how to identify dragonflies is to
(1) Buy a good field guide (or two) (see the Dragonfly Books page)
(2) Get yourself some close focussing binoculars (there are plenty of cheap bins focussing down to 1.5m or even 1m)
(3) Read your field guide(s) and in particular read the detail in the text rather than looking at the pictures,
(4) Get out in the field and look at dragonflies.
It's an iterative process - repeat steps 3 and 4 as much as possible (use the rainy days for step 3 and the sunny days for step 4). You will make mistakes and you will re-read the fieldguide(s) but eventually it will become easier.
By all means take a photograph and display it on your largest monitor. Compare it with ALL the key features mentioned in the field guide. If you're not quite sure then go to a forum or facebook group and ask. Try to find a forum where the responders say 'It's a D because of x, y and z. You could do an internet search for a species that you think your dragonfly is - be warned that there are a lot of images out there (maybe even on this site!) that are wrongly labelled or just plain misidentified.
Don't rely on having to photograph a dragonfly to ID it. You need to reach the situation where you can ID it quickly before it moves on. If you want to survey adult dragonflies (and I hope you will) than you won't have time for photographs during the survey (but you might pause momentarily to photograph a scarce species).
These are very much a work in progress.