After spawn in a jungle, close to you is a desert with some sand hills. But just don’t care about it, start digging down and soon you will fall to the cave system. Explore the cave and you will find plenty of iron, some gold ores. Close to bedrock in the cave and you will find abandoned mine soon.
In the abandoned mineshaft. have other ores too but most of ores is diamond. For example, you will find iron, gold, redstone and lapis. Enjoy!