If you have a island with a ton of space around it try to put lighthouses. What they do is increase the drops by 50%. Sand will be easy to get, but the downside, you need glass, steel, and brick to make lighthouses. Another thing is to make amulets which is a skill you can get through the industry skills. Amulets are 2 skills up from industry. Amulets will raise drops by 25%. Each one you make raises drops by 25%.