General

@OneRockGod Big Spider cancels out Easter Egg Buff, sadly. I learned the hard way today =/

If you can get a monster population +100% core to drop (the best one so really really rare), that helps farming a lot as well as drop rate +30. Beyond that it helps if you kill the monsters as fast as humanly possible, even when they aren't gravitating towards the center. The more monsters you're able to kill in those 30 minutes, the more chances you have at more coins dropping. Also having a big spider or mutant ribbon pig familiar helps the drop rate as well. I get 100+ coins per 30mins on 30% population and 20% drop with my familiar.

Edit: @OneRockGod Just so you know, drop rate familiars cancel out the easter buffs, or any drop rate increase that appear in your buff list.

Make a Kanna and use Kishin. That's what I do. Who needs a spawn booster when you get one on the class?

The rate is still pretty slow with a 25% drop and 30% spawn About 2 a minute

Map 3 while using as many drop rate and spawn rate things as you can. Best to have a pet with item pouch.

Link 3, 30%+ monster spawn, any percent drop rate increase
Edit: Also do all the quests every time you go in, some are really easy.