Here are some of the ways I keep my pockets heavy…
If you uncover the skull in Explorer Camp you get 500 coins. You can do this once a day
If you have gotten all the AllyKat shirts from the garden vine, You can still do this once a day for 250 coins
If you have gotten all the emotes from the maze you can still collect all the blue rocks and get 250 coins once a day.
If you like Combo drop (its my favorite game) then playing the Red Rose bush in the garden will get you the most money from that game. I usually can get 150-250 per game and they only last about a minute a game.
If your game is BOUNCE, The Wheel machine in Skytown is the best one for that game. I can usually get 4-5 gold wheels and they sell for 100 coins each.
The number 1 way to get money is BLUE ELIXER. You can get a lot down in the mines. You come out with 40 -50 elixers easily and you can sell them to the Cloud Sprite in Skytown for 60 coins each. You can sell 10 an hour. Thats 600 coins an hour! Even if you just log on for a sec before school and/or before bed you can get 600 coins in, a couple times a day.
Hope this helps!!