Find a flat area to build the farm
Gather villagers, beds, and workstations
Build a secure villager holding area
Place enough beds for the villagers
Place enough workstations for the villagers
Keep the villagers linked to their beds and workstations
Add a zombie or other scare source if required by your version
Build a spawning platform near the villagers
Add water channels to push iron golems toward a kill chamber
Place lava or another killing method in the kill chamber
Add hoppers and chests to collect iron and poppies
Spawn-proof nearby areas so golems only spawn in the farm
Test the farm and make sure villagers can sleep and work
Keep the farm loaded while you want it to run