Crossroads
By Cream

These three riffs are repeated throughout the song in standard blues progression(1111,44,11,5,4,11)

Riff A
G:---------------------------
D:----5-3-5-3-535------------
A:----------------------5----
E:--3 ------------------------

Riff B
G:----7-5-7-5-7575------------
D:----------------------7-----
A:--7-------------------------
E:----------------------------

Riff C
G:----9-7-9-7-9797------------
D:----------------------9-----
A:--9-------------------------
E:----------------------------

Play in this order:

Riff A x4
Riff B x2
Riff A x2
Riff C x1
Riff B x1
Riff A x2

Repeat through the song

During the solo, the bassist improvises around the twelfth frets, just remember to keep the rhythm of the song.