How do you discover insignias? And what mats do you guys recommend stocking up on?
You don't discover insignias. As you level your crafting skills, new tiers of insignias will automatically be added. You'll notice them as red at first because they show 5 points before you can use them. Once they turn orange, you can use 'em.
You'll mostly need metal and cloth for armorsmithing, metal and wood for weaponsmithing, and fine crafting materials for both.
For the first tier, off the top of my head, you'll need tons of:
Weaponsmithing - Green Wood Logs Copper Ore Tiny Claws, Fangs Vial of Weak Blood
I've kind of given up on tradeskills for now. It seems like the amount of sheer farming required for one tier of tradeskill levels is equivalent to like 3-4x the amount of adventuring. Nothing I could make would catch up to my current level? Am I doing something wrong? The guides I saw list dozens of monster/enemy drops, and leather/silk seem rare even if I salvage every last piece of armor I get.