Once you've learned your local birds and begun making lists, probably you'll find yourself "bird listening" more than "bird watching." Especially during spring and summer, it's much, much easier to identify the various species by song than by trying to see every bird's field marks.
For this reason, good field guides describe as well as they can each species' song. Unfortunately, many of these descriptions are pretty hard to interpret. The best way to learn songs is to spot a bird with your eyes, watch it as it sings, and do this often enough for your brain to make the connection between the song and the bird. It's also a good idea to add in your field guide your own notes describing the songs. Recordings of bird song can be bought. The announcer says "Rufous-sided Towhee," and then you hear a few seconds of the towhee's "drink-your-tea" song.
Especially during spring migration when trees swarm with various species of warbler, vireo, and other migrants, it's a pure joy to walk through the landscape hearing all the various songs, and knowing exactly who is where. But it takes lots of practice...