While I do enjoy the challenges and creativity of writing my own songs, my primary reason for picking up my instruments has always been to play songs that I (and others) really like that I didn't write.
If, like me, you want to learn those crowd-pleasers from great songwriters that have come before as quickly and easily as possible, then I would like to share my method for learning a new cover quickly and easily.
The Steps included in this post are: 1) Prepare Your Materials, 2) Learn the Chords, 3) Learn the Rhythm, 4) Learn the Lyrics, 5) Hum and Play, 6) Sing and Chord, 7) Put it All Together. As you get more experienced at your instrument, you can combine steps, but the above is a systematic way of learning songs. It is guaranteed to get you there, quickly, while avoiding discouragement.
1) Prepare your materials. In the age of the internet, it is fantastically easy to learn almost any song you want to learn. You won't even have to figure out how to play the song yourself, someone has probably already done that for you! A quick search for "(song title) + chords + lyrics +(instrument)" will usually return you a chord chart mapped to the song you want to learn. Also, since my brain does really interesting things to songs in memory, I also usually like to pull up a YouTube video of the song, as performed by the artist, so that I can remember how they do it. You can always make it your own version later.
2) Learn the Chords. Once you have listened to the song (a couple times) and have the chords and lyrics pulled up, it's time to make sure you know all the chords. Quickly scan the document and make sure you know all the chords. If you don't it's time to pull up your chord chart and learn. Incidentally, this is a great way to build your repertoire of new chords. Practice rolling through the song and making the chord changes. If you have difficulty with a change, go back and forth between just those two chords until you can get it feeling comfortable. For more difficult chords this can take some time, remember to be patient with yourself and have fun. I like to make a repetition goal for myself, like making the change 50 times. By then I almost always have it.
3) Learn the Rhythm. Depending on the song, this can be pretty easy, or pretty challenging. To get the rhythm of the song down, I recommend playing the YouTube video while listening for the chord changes. Once you can get to the right chord at the right time consistently, you can start to look for the rhythmic patterns. If you haven't learned a strumming pattern that fits this song yet, you can keep it simple for now. Learning a wide variety of strumming patterns for your instrument is key to learning songs quickly. Try to include a new pattern into each of your practice sessions until you have a good number. If you are having trouble figuring out which pattern works for this song, your teacher will be able to help you choose one that fits.
4) Learn the Lyrics. For some reason, this is always the most challenging and the most fun part for me. You might have a natural head for lyrics, but this is always the most time-consuming part of learning a new song for me. The fastest way I have found here is to read the lyrics a few times while the song plays in the background. As soon as possible, try to get "off book" and remember the lyrics without reading them. Breaking the song into pieces in your mind can help (verse, chorus, bridge, etc.). Just like when you were practicing the chord changes, if there are lyrical transitions that you have a hard time with, pause and practice them until it flows out easily. There isn't really a shortcut for this step, just keep singing the lyrics over and over again. Your brain will naturally make the connections.
5) Hum and Play. Now that you know how the lyrics go with the chords, it's time to hum and play. This step will help you to get over any syncopations in rhythm, and match the tune with the chords.
6) Sing with Chord Changes. This is like the reverse of the last step. In this step you practice the lyrics, but not necessarily with the full rhythm of the song, just matching the chord changes with your lyrics and tune.
7) Putting it All Together. By now you should be ready to sing and play the song together. At this stage, it's just practicing it until all the transitions are smooth.
There you have it. That's the quickest and easiest way that I have discovered to learn a cover. As I mentioned briefly, the more practiced you get at the process, the more you can condense or remove steps. Pretty soon you will be an expert at adding new songs to your repertoire.
If you have any questions or other suggestions please post them in the comments! Thanks for reading and happy practicing!