The most time effective any easy farming method that can also be done by new players.
Do this mission on Earth.
What to Look For
You want to find the 3 caches that are optional for completing the mission, each cache will give you 1 neurode each.
The caches look different from the others, they are a brighter white colour with a white light, they aren’t out in the open and are in specific hidden portions of the map, its a rank 8 or 10 mission so you can just one tap the enemies and finish it in under 3 minutes once you get in the rhythm of the farm. I would say this farm will get you a minimum of 6 neurodes every 10 minutes.