there is a trick to mining.
If you "undermine" example a copper vain so it hang 100% free in the air and hit it 1 time.
It is more easy to mine all of the earth/dirt around the metal vaine vs mining the metal itself. your pickaxe last longer and its faster. Often the copper vain go deep below ground but most players dont see this.
Often there are allot more metal than most players discover in each vain.
Also what people also dont realize is that if you take the "wishbone" you get after defeading a boos then you can find iron and silver. Example you can find iron in the swamp area outside and not only in the crypt..
But yes later on it become harder to find example soft tissue that you mostly find inside the skull of giant skelletons scattered over the mistland biome.
There should also be some dwarf mining camps with soft tissue to mine but i never found any of them. In general mistlands just is tough due to the terrain and bad visibility.

ps. regarding being attacked by wolfs and such things in the mountain.. take some wood with you can build a protective wall around the hole you dig in.
tip. a good way to fight most creatures in the game is to block them with your shield and then hit them one time and repeat.
Also if you press C and crounch then if you hit something with the bow that have not detected you then you can one shot many animals.. Use your ears you can often hear the animals from quite far away.