The key to this is to practice this:
    G                                 
E|---------------------------------|
B|---------------------------------|
G|-------0------0------0------0----|
D|-----0------0------0------0------|
A|---------------------------------|
E|--3------3------3------3------3--|

and this:
    C         G                         
E|------3--------|
B|------1-----0--|
G|--0-------0----|
D|--------2------|
A|----3----------|
E|------------3--|

and then mix them like this:

[Intro]
    C         G                 C         G                 
E|------3---------------------------3-----3------------------|
B|------1-----0---------------------1------------------------|
G|--0-------0------0------0-----0-------0------0------0------|
D|--------2------0------0-----0-------2------0------0------0-|
A|----3---------------------------3--------------------------|
E|------------3------3------3-------------3------3------3----|

    C         G                           G
E|------3-------------------------------------------------|
B|------1-----0-------0-------------0---------------------|
G|--0-------0-----0-------0-2---2-------2-0----0------0---|
D|--------2-----0-------0-----0-------0------0------0-----|
A|----3---------------------------------------------------|
E|------------3-----3-------2-----2-------3------3------3-|