Minecraft wiki entry for Snow_farming, associated text: Include hoppers to collect snowballs and feed them into chests when the player's inventory is full
Add a hopper minecart under the floor block for the same purpose
Make a mechanism to dispense extra shovels into the player's hand, as existing shovels break.
Make the area around the snow golem larger, so that more snow can be produced, and the golem won't be confined so much.