This song, like most of Neil's acoustic numbers, should be played clawhammer style: 

downstrokes are hit with the edge of the thumb or pick, upstroke hit with middle 

finger (held in shape of a 'claw'). Downstrokes are marked ^



Intro:

   ^       ^       ^       ^       ^       ^       ^       ^

d|-0-------0---0---0-------0-----|-0h3---------3-------3-------3--|

A|-1-------1---1---1-------1-----|-1-------1---1---1---1---1---1--|

F|-0-------0---0---0-------0-----|-0-------0---0---0---0---0---0--|

C|-2-------2-------0h2-----2-----|-2-------2-------2-------2------|

G|-3-------3-------3-------3-----|-3-------3-------3-------3------|

D|-------------------------------|--------------------------------|



  ^       ^       ^       ^       ^       ^       ^       ^

|-3-------3---3---3---1---1-----|-1---1---1---0---0---0---0---0--|

|-1-------1---1---1---1---1-----|-1---1---1---1---1---1---1---1--|

|-2-------2---2---2---2---2-----|-2---2---2---2---2---2---2---2--|

|-3-------3-------3-------3-----|-3-------3-------3-------3------|

|-------------------------------|--------------------------------|

|-------------------------------|--------------------------------|



  ^       ^       ^       ^       ^       ^       ^       ^

|-0-------0---0---0-------0-----|-0-------0---0---0-------0------|

|-1-------1---1---0h1-----1-----|-0-------0---0---0h3-----0------|

|-2-------2---2---2-------2-----|-0-------0---0---0-------0------|

|-2-------2-------2-------2-----|-2-------2-------2-------2------|

|-0-------0-------0-------0-----|-2-------2-------2-------2------|

|-------------------------------|-0-------0-------0-------0------|



  ^       ^       ^       ^        ^       ^       ^       ^

|-2-------2---2---2---0---0---2--|-2---2---0----------------------|

|-3-------3---3---3---3---3---3--|-3---3---3---3---3---3---3---3--|

|-2-------2---2---2---2---2---2--|-2---2---2---2---2---2---2---2--|

|-0-------0-------0---0---0---0--|-0---0---0---0---0---0---0---0--|

|--------------------------------|--------------------------------|

|--------------------------------|--------------------------------|

[ Tab from: http://www.guitaretab.com/n/neil-young/251696.html ]

Verse

  ^       ^       ^       ^        ^       ^       ^       ^

|-0-------0---0---0-------0------|-0h3---------3-------3-------3--|

|-1-------1---1---1-------1------|-1-------1---1---1---1---1---1--|

|-0-------0---0---0-------0------|-0-------0---0---0---0---0---0--|

|-2-------2-------0h2-----2------|-2-------2-------2-------2------|

|-3-------3-------3-------3------|-3-------3-------3-------3------|

|--------------------------------|--------------------------------|



  ^       ^       ^       ^       ^       ^       ^       ^

|-3-------3---3---3---1---1-----|-1---1---1---0---0---0---0---0--|

|-1-------1---1---1---1---1-----|-1---1---1---1---1---1---1---1--|

|-2-------2---2---2---2---2-----|-2---2---2---2---2---2---2---2--|

|-3-------3-------3-------3-----|-3-------3-------3-------3------|

|-------------------------------|--------------------------------|

|-------------------------------|--------------------------------|



  ^       ^       ^       ^        ^       ^       ^       ^

|-0-------0---0---0---0---0------|-0-------0---0---0---0---0------|

|-1-------1---1---1---1---1------|-0-------0---0---0---0---0------|

|-2-------2---2---2---2---2------|-0-------0---0---0---0---0------|

|-2-------2-------2-------2------|-2-------2-------2-------2------|

|-0-------0-------0-------0------|-2-------2-------2-------2------|

|--------------------------------|-0-------0-------0-------0------|



  ^       ^       ^       ^       ^       ^       ^       ^

|-2-------2---2---2---2---2-----|-2---2---2---2---2-------2---0---|

|-3-------3---3---3---3---3-----|-3---3---3---3---3-------3---3---|

|-2-------2---2---2---2---2-----|-2---2---2---2---2-------2---2---|

|-0-------0-------0-------0-----|-0-------0-------0-------0---0---|

|-------------------------0-----|-----------------0---------------|

|-------------------------0h2---|-----------------0h2-------------|



Play this with variations throughout (e.g., Em to Em7, D to Dsus2, etc.)



Other parts of song have straightforward picking pattern:



(G) 

Oh, Isabella, proud Isabella, 

(Am) 

They tore you down and ploughed you under 

(Bm)                                  (C)

You're only real with your make-up on 

(G)                              (D)

 How could I see you and stay too long