With dragons you want Air defences that are close together, or near the edges. . If you can get one with air defences near the edge and archer them out, that base is yours with 5 dragons spread thin. If they are close together, you drop a heal as your dragons approach, and you drop a rage to get the Air defence done as quickly as possible.
Ignore the rest at TH8, just try and get Air defences ASAP and dragons will take the rest for you.