I know this is the right way, because it comes straight out of the Metallica guitar tab book.

Intro: (clean)
E)--------------------------------------
B)--------------------------------------
G)-------------------------------------- Repeat 12 times
D)--------------------------------------
A)--------7-------7---------------------
e)--0-0------6-5------------------------

Intro cont' (distorted)
E)--------------------------------------
B)--------------------------------------
G)-------------------------------------- Repeat 4 times
D)--------------------------------------
A)---~7--------~7-----------------------
e)------000000----000000----------------

Intro cont'
E)--------------------------------------
B)--------------------------------------
G)--------------------------------------
D)--------------------------------------
A)--~7--------7---------7---------------
e)00-----00-----6-5-00-----65-00--------

Main riff( repeat throughout song till end)
E)---------------------------------------
B)---------------------------------------
G)---------------------------------------
D)---------------------------------------
A)--------7--------------7-----------------
e)--0-0------6-5---0-0------6-5---------