User blog comment:TheScottBird/I Need Some Help/@comment-24972506-20140929151822

OK. I am at max level, have all islands, every Ethereal monster, my overnight coin production is over 5.6 million, so I do have experience, eh?

I think there are some tutorials for newbies, but you are past that, so, taking from where you are:

1. Sadly, bringing one-element and two-element monsters to 100% happiness does not pay off. Their rate of coin production is too low no matter what. At least you have not made them bigger than Level 4, so KEEP THEM THERE, DO NOT FEED THEM ANYMORE.

2. Feed your 3- and 4-element monsters to Level 9, but no higher. This maximizes coin production while conserving food. To do this, do NOT upgrade Air Castle now, instead, bake Pizzas (fastest rate of food production, without upgrading to Large Bakery) on all islands, keep baking and feeding until all your 3- and 4-element monsters are at Level 9 (but no higher).

3. Starting with cheapest Decorations first (yeah, I know, easier said than done, but do the best you can), get your 3- and 4-element monsters to at least 75% Happiness, preferably 100% for your 4-element monsters. And the Congle, which has by far the best coin output of any 3-element monster. Again, this is all to maximize coin production. Just do not spend over 200,000 coins on any one decoration, at this stage of the game; the payback period is too long.

4. Keep breeding for more 4-element monsters - it costs nothing to breed, if you don't get one you can sell unwanted offspring for some coins, and the 4-element monsters are your big money-earners. Do NOT keep more 1- and 2-element monsters, they are not worth it.

5. Keep trying for the Ethereal monsters - again, it costs nothing to breed, if you don't get one you can sell unwanted offspring for some coins, and the Ethereal monsters will be by far your biggest money-earners. Plus, eventually, you can start populating Ethereal Island (but not for quite a while, they do not earn coins there and for quite some time you will want to concentrate on the other "natural" islands).

6. Quit razing the lands. It just wastes coins, and you have plenty of space for all the monsters for now. Plus, you'll wish you'd kept some trees come the holidays.

7. Buy mini-mines as soon as you can. You WILL need lots of diamonds later for Castle upgrades, and the way to get them for free is to have those mines.

8. Buy more Medium Bakeries as soon as you can. In the short run, invest your coins in baking and feeding your monsters as stated in #2 above.

That ought to keep you happily busy for a while :-)