Farming the underworld is a bit hard to teach as its more of a thing you get the feel for. You begin to learn what to look for. Realize what base shapes and coverages will be worth it and which ones wont. You get to know goblins like no other at times placing them super far away at an exact spot even if it means elthey get shot just so you can get the storages without giving them a sheild ect.
Ultimate look for 1k per gob or more and unless the 10k gold is real easy i usually skip it. Usually I'm aiming to stay above the 20k gold per raid and around 2 mil an hour of none stop raiding.

