Terraria – What are the easiest good pickaxes to get and how do you get them

You can go exploring some corrupted/crimson areas (randomly picked at world generation) to destroy the shadow orbs/crimson heart waiting for you at the bottom of chasms.

Each shadow orb/crimson heart destroyed will provide you some loot, and make a meteorite land on the world. Once the meteorite has fallen, go find the site, and mine the meteorite ore. This will allow you to craft some meteorite gear and weapons.

Once you've destroyed three shadow orbs/crimson heart, it will make the Eater of Worlds/Brain of Cthulhu spawn, allowing you to fight two different bosses.

Note: The shadow orbs are protected behind some ebonstone/crimstone, which you will not be able to mine with your current pickaxe. Just buy some dynamite from the Demolitionist and use it to access the shadow orb. Or you can buy purification powder from the Dryad, which turns the ebonstone/crimstone into the easily destroyable standard stone.

As of 1.1.1, this is a complete list of all things immune to Dynamite (and Bombs, too):

• Dungeon Bricks of any color
• Any type of Chest (including Barrels and Trash Cans), even when empty
• Demon Altars
• Cobalt Ore
• Mythril Ore
• Adamantite Ore
• Hellstone, but only before the Wall of Flesh is defeated

Additionally, unsafe background walls (such as natural Dirt or generated Dungeon Brick Walls) are immune, unless the explosion reaches the edge of (or a hole in) the wall.