Cleaning out inventory for crafting and gathering?

I will soon have to try my hand at the DoL/DoH classes (most of my battle classes are approaching 50), and I'd like to clean out my inventory but I'm just not sure what I'll need for, say, Coil, when/if I decide to do it.

I have basically hoarded everything I've ever gotten from quests, including a few varieties of ward potions, lots of different stat boost potions, healing potions and ethers, elixirs, etc. So what of all of this is absolutely needed?

On top of this, I have several varieties of food items that I think I can sort through on my own.

Also, one of my retainers is holding all the drops I've gotten over the months that are presumably "crafting materials".

I'd encourage you to straight up place everything in your retainers on the marketboard if it A) Sells for at least 1k, and B) Is not a crafting material. You can always buy a new one if in the future you need it.

Ok, that answers one question. I'll look here in a bit at what all I have. I'm going in blind so I have no idea what things I'll need and what things are truly "vendor trash". About all I've heard is karakul farming is a thing. I'm sure my retainer has at least one full stack of animal... hides? skins? Can't remember exactly. He's sitting at 169/175 though. My personal inventory floats at about 75-80, with one page of potions and another 2 of food. Again, not sure what's worth what in the potions category. Do I just keep the largest variety of potions or do the smaller varieties get used in recipes?

Potions aren't used at all in crafting, and the only gathering potion is Cordial, which can't be crafted. Even food isn't necessary until 1- to 2-star recipes. So, only bother to save the most powerful HP/MP restoring potions, mega-tier stat-boosting potions for jobs you care about (only if you use these, though), any Cordials you might have, and food with combat bonuses you care about.

For the first 15 levels or so of each craft, you will buy every ingredient you'll need from the guild suppliers and tradecraft merchants in your crafting class's city. Karakul skins are useless, but Fleece (from Ornery Karakuls) is required for Weaver after level 35. Animal skins and hides are used in low-level Leatherworking, but they can also be bought from the LTW guild supplier.

Basically just pick a craft, and the class quests and levequests will ask you to make stuff so you have an idea of what to do. (Shameless plug: I wrote a FAQ. It's from 2.25 right now, but it should be updated to 2.38 within the week.)