Ok, when you mine, you worry about monsters, or monsters in the night. I can help you!

Step 1: Go on creative mode

Step 2: Spawn some zombie or creeper or any mob eggs.

Step 3: Punch them or kill them with a sword that is wooden!

Step 4: Do this until you go in a cave

Step 5: Mine all ores in the cave

Step 6: Mine caves in Survival

Step 7: DONE!