Crafting and Gathering
Buy a mining pick from the provisioners and stand next to a mountain. Press u to use, select the pick, then press the arrow key in the direction of the mountain. Hold down F9 to mine the same spot again. Don't catch the black lung.
If you're really lucky you might dig up a gold nugget, otherwise you'll just dig up ore, the colour of which will depend on your skill. If you're unlucky, you may unearth an angry Zorn.
More on Mining here.
Woodcrafting is the combined skills of lumberjacking and of making wooden items, such as staves, torches, and bows. To aquire the raw materials (i.e. logs), use a woodsman's axe in the forest and you might, depending on your skill, chop a log. Careful, however, as you may disturb a Wisp.
More on Woodcrafting here.
Fishing requires a fishing rod, available at the provisioner.
To smelt ore into ingots, use (u) a pair of smelting tongs in the direction of a brazier whilst having ore in your inventory.
To make metal weapons and armour, use (u) either a smith's hammer or an armourer's hammer on an anvil whilst having ingots in your inventory. A list of items will then appear that you can make, once again according to your skill, and how many ingots you have.
As mentioned previously, Woodcrafting is the combined skill of logging and creating wooden items. To do the actual item creation, get yourself a pocket knife and use it to carve wooden things. You will need to have logs in your inventory to make anything.
More on Woodcrafting here.
Alchemy is all about making potions, processing potion ingredients and converting or tinting different Item Materials. Alchemists are dependent on tinkers to make most of their processing and potion tools.
More on Alchemy here.
Cooking is divided into a gathering and crafting skill. The butchering of monster corpses is essential for various recipes that can be made via cooking with the proper kitchen implements on stoves, campfires, and braizers.
More on Cooking here.
Tinkers specialize in the creation of crafting tools and other knick-knacks. From studs for studded leather to probes and lockpicks. Their ability to make items that almost every other craft is dependent on makes them pretty important.
More on Tinkering here.
Tailoring is the art of making cloth and leather items. To get started, buy a sewing kit from the provisioner, get yourself some cloth (or leather) and get sewing!
More on Tailoring here.
Inscription is the ability to create scrolls. Scrolls of identify, uncurse, town portal and a few of the spell scrolls are included.
More info on Inscription here.
Enchanting is an advanced skill which gives the ability to create magic items with a broad range of special effects. Enchanting uses the captive souls of dead monsters and many other ingredients. Generally, more powerful magic items require stronger captured souls.
More on Enchanting here.
Bonecrafting is a necromancy only skill that allows them to craft all sorts of bone trinkets, armour, weapons and potions.
More on Bonecrafting here.