I think the best solution in the early game is to explore your starting biome and search for shallow caves that contain treasure. You'll likely find a boomerang early, which can be useful as a ranged and indirect fire weapon early in the game.
Once you've come across a few chests and have a bit of gear/weapons, start digging a shaft. Explore caves and fight enemies, which will probably yield some amount of cash plus opportunities to mine ores you can use to forge better equipment. Better equipment will allow you to dig deeper and/or explore some of the neighboring biomes, which will yield opportunities for even better gear.
Money's not super important as most of the gear in the game can be crafted or found as treasure. You will need to purchase items from time to time, so make sure that you occasionally make time to satisfy the conditions for NPCs to arrive.
Lather, rinse, and repeat until you're epic and difficult to kill, and then you can tackle some of the more exciting boss fights and deepest regions of the world. If you're at a loss as to what to do next, or how to craft some of the higher level gear, go dig around a bit at one of the Terraria Wiki sites, which contain info about all sorts of interesting artifacts.
Death is relatively cheap, as long as you leave as much of your money as possible at home. Don't be afraid to go and explore something new, you might luck out and find a valuable artifact. The worst case scenario is that you end up a tasty snack for something big and nasty, and maybe lose a few coins.
The goal of this game varies depending on what your goal is, so don't be afraid to do something risky or try something new if you're having fun! If the game is getting frustrating, try exploring more closer to the surface, or looking up a strategy for dealing with the particular situation you're stuck on.
Halloween Mode specific items:
NPCs:
- The Merchant: sells a sickle for 1 gold. When used to cut grass, it harvests hay.
- The Arms Dealer: sells the nurse's outfit (hat, shirt, pants), 3 gold per item.
- Witch Doctor: sells the cauldron for 1.5 gold. This is basically a re-skinned cooking pot.
Drops:
- Bloody Machette, a harpoon category weapon. This has a .05% drop chance.
- Bladed Glove, a claw weapon with high knockback. This is also a .05% drop chance.
- Goodie Bags, of course. They drop 1.25% of the time.
The only other difference in Halloween Mode is that pumpkins grow naturally on grass surfaces. You can now buy pumpkin seeds year round though, so you'll always have access to pumpkins if you have money to spend.
Best Answer
Those are Rubies. In addition to appearing in stone, gems can be found attached to the sides of other blocks, particularly in a Gemstone Cave. You can harvest them with your pickaxe directly, or by breaking all the blocks next to them.