So keep yourself at level 1 and 3.

DO NOT go to the 5th leve of the mine, The monster are WAY too strong for you there. Just keep yourself at the 1st and the 3rd level and you should be just fine~!

After You've mined for awhile you'll probably wonder what all the minerals are for. Well, You need them to upgrade your weapons.
To upgrade your weapon you'll need a skill for it and you can only get Latale Ely from Valt inte the belos Weapon shop when you turn into level 10.
However, there is alot of other stuff thats good too that you can get form Valt and Keber. Keber wil give you the ability to craft weapon, accecssorys or Sheilds and Valt will give you the ability to either Upgrade your equipment or Enchant them. Choose wisely.
Upgrading your equipment will make the change to a stronger weapon/piece of clothes. For exempel, If I upgrade a Long Spear(Level 4 weapon), It will become a Iron Long spear(Level 9 weapon) and if I upgrade that, It will become a Winged spear(Level 14 weapon). You got it?

To upgrade your equipment you'll need a weakest, weak, medium or strong Capsule. You can get Latale Ely  from any local General store ownsers. (Like Esther in Belos.)
Open up the Upgrade window by pressing this button on the bottom of you Inventory:

The Upgrade window will pop up and you can put in your weapon.
SMALL NOTE: Just place the equipment you're gonna upgrade into the the upgrade window and itwill show you wha items you'll need to upgrade your equipment. For exempel, When I put in my Kuk spear it will show me that I need a Weak Capsule and 3 Silver.
Put in your equpment you want to upgrade, put in the mineral and the Capsule and then press Execute.
If you're lucky it will become a success! Hurray!

This is how it will look like when you're upgrading something.

I feel extra nice today, so I'll throw in a small guide on how to Enchant your weapons and other equipments.
Right next to the upgradig button there should be a button tha says "Enchant Items".

You'll need puzzles to enchant items.
You can get Latale Ely either from monstrs dropping them or by buying a Puzzel Cupon in the Fashion Shop and trade it for a puzzel from a NPC in town.