On the third line of each verse I like to throw in a descending
line on the high e string, G# -> G -> F# -> F which you can just
play with your fourth finger.
It helps if you alternate the bass between the fifth and the root
every beat i.e. call alternate the Am with Am/E and C with C/G. 
Where I've indicated a C/G I mean to play the whole thing without an
independent bass.  Also, you should embellish the solo tab at the bottom quite a lot if you can.
Chorus goes between each verse, sometimes it goes verse chorus solo chorus verse if you like.

* means to play an Am and stick a G on the E string every fourth
beat. You can hear what I mean if you look up the Irish Brigade
version online.

Am                               C                Am
Well I have been a Provo now for fifteen years or more
   Am                          C/G     
Of Armalites and mortar-bomb I thought I knew the score
    Am
But now we have a weapon we've never used before
    F (1st fret)              F (8th fret) Dm               *
The Brits are looking worried -  and they're going to worry more
 
Chorus
Am           C/G                (slide down)
Tiocfaidh Ar La! Sing Up the RA!
*
OOH! AH! UP THE RA!
F (1st)  F (8th) Dm     *
SAM missiles  -  in the sky
 
I started off with petrol bombs and throwing bricks and stones
With a hundred more lads like me I never was alone
But soon I learned that bricks and stones won't drive the Brits away
It wasn't long before - who did I join? - I joined the IRA!
 
And then there came internment in the year of seventy-one
The Brits thought we were beaten, thought we were on the run
On that early August morning they kicked in our back door
But for every man they took away - how many did they miss? - they missed a hundred more!
 
I spent eight years in the cages, I had time to think and plan
For though they locked away a boy, I walked away a man
There's only one thing I learned while in their cell I lay
The Brits will never leave us - until when? - until they're blown away!
 
All through the days of hunger strike I watched my comrades die
While in the streets of Belfast you could hear the women cry
I cant forget the massacre that Friday at Loughgall
I salute my fallen comrades - as I watch the choppers fall

Solo melody (low E string):

t for triplet
----------------------------------------|----------------------------------------|
--------t---------t---------------------|----------------------------------------|
------_______---_______-----t-----------|------------------------------t---------|
------|-----|---|-----|---_______-------|---------t---------t-----0--2-2-2----2--|
----0--0-0-0--2--3-3-3--0-|-----|-------|----0--0-0-0--2--3-3-3-------------3----|
-0-------------------------3-3-3--0--3--|-0--------------------------------------|

-------------------------------------------|---------------------------------------| 
---------------t---------------------------|---------------------------------------|
-------2--2--2-2-2-------------------------|---2~-2~-2~-2~-------------------------|
-0--2---------------2--2----0h2--0h2-------|---------------------------------------|
--------------------------------------3--0-|---3~-3~-3~-3~-------------------------|
-------------------------------------------|-0-1~-1~-1~-1~-1///7--7h8-7h8-7--3--5--|


Solo melody (high e string):
      t            t            t                  t            t               t
-0--5-5-5--7--8--8-8-8--5--3--3-3-3--0--3--|--0--5-5-5--7--8--8-8-8--10--12--12-12-12--8--12-|
-------------------------------------------|-------------------------------------------------|
-------------------------------------------|-------------------------------------------------|
-------------------------------------------|-------------------------------------------------|
-------------------------------------------|-------------------------------------------------|
-------------------------------------------|-------------------------------------------------|

             t
-----5--5--5-5-5----------t--------------|----------------------------------------------------|
-3/5--------------5--5--5-5-5--5\3--1----|-- Last bar of this is the same as the last bar of--|
---------------------------------------2-|---the low version.---------------------------------|
-----------------------------------------|----------------------------------------------------|
-----------------------------------------|----------------------------------------------------|
-----------------------------------------|----------------------------------------------------|