Watching how a bird acts, eats or flys, helps you learn to identify birds. One of the main skills to be acquired by the birder is learning to watch how a bird acts and to recognize certain behaviors.
There is a most informative online guide by The Cornell Lab of Ornithology. In the section All About Birds you will find information to develop birding skills by learning the birding basics.
This site has user friendly pages that discuss how a bird's posture and size, movement, flight patterns, feeding styles, habitat, using range maps, time of year, field marks of the head, field marks of the wings, songs and calls, can make identification much easier. There are tips for beginners and information about how to use eBird.