If you’ve ever read about how to improve your identification skills, you have undoubtedly run across these suggestions: Continue watching after you’ve identified the bird. Leave your field guide at home. Take notes or draw sketches. Get to know common birds.
The suggestions are all related. Their ultimate goal is to increase your engagement, focus your attention, and encourage you to look more carefully, so that you see (and remember) more details. My hunch, however, is that they are either too vague (“get to know common birds”) or too ambitious (“draw sketches”), and most birders probably never even get started.