Kalopsita/Global/Economy Guide for New Players

Save your Skystones for refreshing the Secret Shop. This is a major source of Mystic Medals, which is used to summon powerful ML5s.
Save your Leifs for buff events to get more out of your energy. If possible, try to save some Leifs for high-value events that give you repeatable rewards for spending lots of energy.
Imprinting 3-stars to SSS is an easy way to get large amounts of Covenant Bookmarks from Reputation missions. (Note that the total amount of times you can do this is finite.)
A good way to get quick gold is to buy Penguins with Stigma, and sell Penguins in your Inventory. For the best place to farm Stigma, look up video guides that will tell you the best stages for money farming.
Climbing up in Arena will give you one-time Skystone rewards, as well as weekly Skystones based on your rank.

Focus on farming hunts first in order to gain gear. When in doubt, follow the beginner missions!
If you don't have Fenne (the most powerful PvE DPS for many scenarios), make sure she is on your standard wishlist. Or pick her from any selector if she happens to be available. Other important PVE units can be obtained for free from beginner missions.
When crafting gear with hunting materials, focus on producing high quality "left-side gear," i.e. Helmet, Sword, Chest. These pieces have fixed main stats, and thus has one less layer of RNG involved when crafting.
For right-side gear (i.e. Ring, Necklace, and Boots), it is better to obtain them through guaranteed sources such as Events, Arena Shop, Equipment Conversion, etc.
Save your Equipment Modification Gems until you understand when to use them. It is possible to ruin good gear by using them unwisely.

The following 3-star artifacts are valuable, and it's worth having more than one maxed-out copy: Daydream Joker & Prophetic Candle.
The following 4-star artifacts are super valuable, and it's worth having more than one maxed-out copy: Tagahel's Ancient Book & Aurius. In fact, these are valuable enough that you might want to keep two or three copies before you start using them to Limit Break. Never sell any copies of Tagahel's. It enables Soulburns that help you gain the upper hand in PVP.
Always buy Bottle of Knowledge from the Powder Shop whenever it's available. This will help you Limit Break any Artifacts you get from Limited Banners.

Try to create a pet with S-rank skills as fast as possible to get more out of your farming. Lobby pets also give you daily gifts,. If they are 5-star, the gift has a chance to be more valuable!
- Pet Tip: Don't release your 1-star pets! The best way to find S-rank skills is by synthesizing them together and not choosing skills. This will allow you to reroll skills. and it's recommended to reroll pets to up to 3-stars before releasing them.
- Don't underestimate the value of 3-star heroes. For general PVE, some of the best units are 3-stars! Commander Lorina; Ainos 2.0; and Camilla are examples of must-build 3-star units.