When your in survival you can mine down to block 12 to have a good chance for diamonds. You can check your block by pressing f3 on a pc and fn f3 for a macbook . When you’re in a village you can mine all the hay with a hoe and turn the hay in to wheat and turn the wheat to bread for a long time of food. When you are in a cave bring a lot of wood and craft a crafting table to make some tools and other items.