Soul sand was easy, but I can't find netherwart anywhere. So, I fed all my reputation to the random number gods and eventually got one. I just have to not die for a while.
How the hell do you get started out in blight fall?
Start in one of the easy domes. Alpha is good, but it doesn't matter that much because you can access the others easily enough.
Do Instructor quests, including the tutorial ones if you don't already know Tinker's Construct. You'll need to leave the dome to go to the swamp to get clay, otherwise you can get a solid start without putting yourself in any danger. If I were to do it again, I'd build my smeltery on the outside of the dome and knock a hole so I can access it, that way I'd have more room for farming. The smeltery isn't affected by taint. Your first goal is to get through the hard metal gate. Soft metal is easy, you can find Promethium below Alpha, but the only hard metal you can get below Alpha is Iron, and you can't make a vanilla Iron pick. So, you're looking for Bronze (copper and tin, all tech metals are very rare but when you find one ore, you can requisition ingots from the Jaded), or something called Oureclass or something which is below the swamp.
Anyway. Get armor, get a sword, do scout quests. Do not go to the later destinations, they tend to have humanoid enemies that can't really be killed yet. Even a hunter is a serious threat. Reputation feels cheap during this phase, but you'll hit a wall when you run out of scout locations, and the repeatable missions from the Colonist don't give you that much reputation considering what they want from you. Your priority now is probably thaumcraft research, though your tools can still be upgraded a lot without too much danger. And set up a varied farm, Spice of Life will heavily nerf your food otherwise.