Whenever you perform a task you will also get EXP. When you get enough EXP you will level up and you will get a boost in the rewards of the tasks FOREVER. That means that the best strategy is to always try to level up. It´s really not that difficult, you could reach level 100 in less than a week (even faster if you get some experiencie ring, wich could drop randomly after each task). If you get an item you can also sell it at the market for as much as 5000 coins depending on the item!
If you level up enough you will be able to reach the minimum coins to cashout multiply times a day without problems.