You may want to consider joining a clan as doing so will offer various rewards.
Endless Mines
Don't forget to check out the Endless mines, these open just once a day and contain unique treasures which cannot be found in regular mines.
Equipment
It is important that before you head down into the mines you equip as much of your best gear as you can as you will need everything you can carry.
Experiment
Try combining items through experiments as there's always the possibility you might invent a custom piece of equipment that turns out to be a game-changer.
Heroic Digs
When you feel you have become proficient at the game you may want to consider having a go at some heroic digs. Although these can be dangerous they will yield great rewards if you are successful.
Inventory
It is important that you make expanding the inventory your first priority as the mines will quickly fill up and you will need that extra space.
Power-Ups and Boosters
Due to their limited supply make sure you only use your power-ups and boosters only when you need them.
Resources
You can always shatter any items you don't really need to gather the resources from them.
Various Tips
Always equip your best gear before heading down into the mines. You'll need everything you can carry. Try combining various items through experiments and you might find some very useful things. Expand the inventory as soon as you can. You will realize how mines quickly fill it up and you really need that space. If you come across items you don't really need, you can always shatter them and gather resources. Clans can offer various rewards, so make sure you join the one you find interesting. When you feel you've mastered the game, take a stab at some heroic digs, which are quite dangerous, but can yield awesome rewards. The endless mines are a daily thing so don't forget to test them out.
Clans...