This fast guitar lesson is going to let you know what it takes to learn a song, and no, it's not going to take months to do it either. The reason that beginning players are coerced to learn practice scales and riffs is because this helps to establish a strong foundation to play almost anything later.
However, if you just wanted to dive right into songs, there's a straight-forward method to focus on your skills on just that song and it's simple to learn. So, let's take a look at 6 things you need to know to learn a new song or tune.

1. How many chords are used and what are they? The odds are that any song that you're attempting to play is based on a simple set of chords and that's what you need to know first. So, get onto the web and type "Your song name's chords" and I'm sure you come up with a long list of results. Try to stick with songs that have four chords at the very most if you're just beginning.
2. What is the song's tempo? Is this going to be a fast or slow tune? For beginners, it's best to start with something slow or at an average tempo of around 120bpm which is considered andante. Any fast guitar lesson will tell you that it's a good idea to use a metronome when you're practicing to keep up with a tempo as well.
3. Does it match my skill level? This step is sort of reiterating what has already been said, but by this point, you need to realize if the song you're going for is too difficult. If it is, don't be discouraged. You'll get to that point eventually, but for now you should try something easier to keep your motivation going.
4. What are the chord progressions and transitions? In this fast guitar lesson I'd like to stress the importance of smooth transitions in a guitar progression. Learn what order the chords come in and how they transition, but as you practice those transitions, make sure that everything is flowing together smoothly. The smoother your transitions, the more you'll be recognized as a professional player.
5. What is the rhythm of the song? Now that you have the chords and tempo down, it's time to tackle the rhythm. This is more about what variations of strumming patterns are used through each chord. Try to sync up as close to the recording of the song as you can to make your playing authentic.
6. What defines the song? This is more a subjective section to this fast guitar lesson, but it's about knowing what to add into the song besides just the base chords. Maybe there's a specific intro riff or lead section that really identifies the tune. Think about what creates the originality of the piece and that's the last thing to learn.

from goarticles.com