Coins are collected from your habitats. They usually some time to fill up, depending on the level of the monsters contained inside. Because habitats no longer produce coins when they are full, collect from them regularly. When you send your Mugwai to work, select the five minute jobs if you have the time. Those jobs are the best choices in terms of coins per unit of produced food or stones. However when you have to leave the game unattended it is better to take the most expensive jobs to maximize the items produced per time period.
Elements
To get the best variety of monsters on your island, breed multiple elements. By doing this you can get a new animal.
Food
Stones are needed them to breed new monsters, but food will level them up. It is also the resource that gets consumed faster. For every one stone job, do three food jobs in order to keep a balance.
Gems
Gems are earned during game play and after achievements are earned. Save them for use for an extra Mugwai to work more fields at the same time. Try to always have four Mugwai at work.
Habitats
After unlocking new of habitats, move all your monsters to it and replace the smaller one to increase your profits. Keep all your habitats full with monsters, even if they are low level and lower rarity. They will still produce a small number of coins.
Layout
Space will be at a premium. Maximize its use by not purchasing any decorations. Place all the buildings close together.
Rare monsters
When sending monsters out to hunt you can increase the chances of getting a rare one by spending material from The Source. Rare monsters produce more coins.