One for the ladies. John Mayer is a tidy lil' guitar player, and this song is one of his easier tunes to play. It's in a kind of pop / jazz style, and mainly involves fingerpicking. Unless you are used to fingerstyle / jazz techniques the fingerings on the chord shapes here will take some work. They're not too bad once you get used to them, but it's quite different to standard chord stuff. Expect some unusual (but nice) chords.
He uses drop D tuning which is easily found from standard tuning. Just play your open D string and then lower your Low E string down (2 notes) until the notes match:
Drop D Tuning: Low D : A : D : G : B : E
Here's all the riffs you need to know...
Verse - Keep your 3rd and 4th fingers on the frets shown. The bass note is the only thing that changes during this little riff. It's a very short riff, and not too awkward but you will need to be familiar with fingerpicking and muting techniques. If you aren't, don't worry, this song will help you get up to speed.
The trick is to mute properly between the notes played. This muting is best done by your fingerpicking hand as well as your fretboard hand. As soon as you have plucked the strings, bring your fingers back to the strings and touch them. This will mute the strings. Plus your fingers will be in the right place to pluck the strings again. This form of muting is a common fingerpicking trick. It gives a little punch to the rhythm.
Chorus - This is played in a similar fashion to the verse, i.e. mainly using your fingerpicking hand for muting. It's also short and repetitive, cycling through a few variations on the same basic chord shape. You can use your thumb to play some notes along the Low D string instead. We show that way here. Use whichever way you find easiest.
Ascending Riff - At the end of the chorus he ascends through this little chord sequence.
Bridge - I love this part. It's all just using 1 chord (C add9 sus4) and as long as you can get the finger stretch with your little finger, it's quite easy to play.
Solo - Really nice solo using a classic jazz style. It uses double stops (2 notes played together) throughout. The little melody he plays repeats twice, so just work on the first half, then repeat it again to finish the solo.
Break - After the solo just keep plucking / muting these 2 notes for a while.
Funky Backing Fill - There is a second guitar that plays the same little riff over and over through most of the song. It's shown at the end (the main guitar just plays the verse / chorus all over again). If you want to play this riff, you'll be better off using a pick. The trick here is to do lots of fast palm-muted downstrokes (you can use alternate strokes, but downstrokes is easier). On the very last double stop, open pick (just remove your palm from the strings) and slide up. Repeat lots.