1. Multiple accounts at the same time: If you have multiple devices that can play games, you can create new game accounts and play games at the same time. In this way, you can get more upgrade materials and sell all the equipment and props you get to other players.

2. Mining: Adventure Island has a mining system, and gold coins and equipment can be obtained by mining veins. However, mining requires some skill and patience, because you need to keep digging to get more ore.

3. Tasks: Adventure Island has many tasks, and you can get gold coins and experience values when you complete the tasks. So, you can try to complete as many tasks as possible to earn gold coins.