You will need:
Pickaxe
Shovel (maybe)
Sword
Torches
Water (2 buckets)
Glass
Ladders.

1- Go to your spawner and clear out all of the zombies, and place torches round the spawner to prevent spawning of Zombies. And then clear away the Chest/s

2- Go and mine out one/two blocks down from the spawner, Also mine 9 blocks from the back wall. Doesn't matter on width

3- Then at the end of the 9 blocks, go to the 9th one a dig down about 4/5 blocks and along 9.

4- On the 9th block dig down 15-20 blocks for the zombies to fall.

5- Make a unlimited water source and get your buckets of water and the lowest blocks with water all the way along.

6- Then drop down to the trout (the 4/5 block, 1 way tunnel thing) and then place a water source at the far block so it flows the 8 blocks.

7- Then make a suitable way to get down to the Zombies to attack them.

8- Make a 2x8 glass wall infront of the Spawner so the zombies are attracted to you.

9- Get lots of XP and Zombie Flesh.

-If you have any problems comment. thanks, REP if this helped please<3-

It should look like this. [ Register or Signin to view external links. ]