Some of you may recall that Leatherworking was a big pain for me on the Beta servers, I tried to level it and gave up around 430. So when it came to level again after Launch, I wasn't exactly hyped about the prospect. However, last week I was able to make my final push from 425-440. I have to give credit to BRK for prodding me on this, his post about Leatherworking helped me see the light at the end of the tunnel :)
I think the easiest way to start out at 375 is by making Borean Armor Kits. You learn them at 350 but they're still yellow at 375, so if you want to cheap out for the few points it's an option. Actually, I suspect the armor kits sell better than the green leather gear, but that's just my theory. I actually used up all of my kits to get cheap stamina buffs for my various toons, heh.
Once you get to 380 you'll be forced to make green armor. If you plan to DE this stuff, then go for what's cheapest to make. On the other hand if you are trying to sell your wares, I'd stick with the rogue/hunter gear (Arctic/Frostscale). My experience has been that DPS gear sells better than healer/caster gear most of the time. And some of these pieces are actually an upgrade for folks who didn't get to run Kara, so you be able to off-load it. As always, try not to flood the market so you can avoid the pricing wars that usually ensue.
You'll continue making green leather gear all the way up to 390, when you'll be able to train the Heavy Borean Leather recipe. Since this little goodie will be used quite a bit later on, feel free to make as many of these as you can stand. The recipe starts out yellow, but doesn't turn gray until 405, so theoretically you could crank all the way up to that. I doubt many folks will have the patience or the mountain of leather needed for that though, lol.
At 395 you'll learn the Heavy Borean Armor Kit recipe, which you can also use to grind up to 405. These bad boys are actually selling pretty nicely on my server, I got 50g a pop for some a few days ago. So I wouldn't feel bad at all making a bunch of these and selling them for decent money. Consider it your payment for the money you probably lost on the green armor from 380-390.
At 405 you begin to unlock the blue (rare) armor and possibly some better money-making options. Now I'll grant you that I was frustrated to see some leatherworkers selling these puppies for as low as 20g a pop, but if you're patient and play it smart you can probably avoid stooping that low. I sold most of mine in the 75-150 range and that was purely through patience. I didn't post anything if there were other insanely cheap ones up. I just waited until there was nothing up and/or others in the price point I felt was workable. So far I've sold all my blue pieces except one stubborn pair of hunter leggings. And as I mentioned above, focusing on DPS items helps a lot. I only sold a couple of the healy Iceborne items, but I sold several sets of rogue armor for good money. The Dark Arctic pieces are actually quite nice for rogues (they rank pretty well on Shadowpanther.net), so take advantage of that.
You'll be making these items for awhile, so it makes sense to find items that will sell on your server. At 400 you'll also unlock the Fur Lining recipes, which allow you to enchant your own bracers. If you plan to do these, go ahead and do it now while the recipes are orange. On the other hand, you could just save your Artic Fur for the final stages since you'll definitely need it later. That will just have to be a judgement call on your part. I went ahead and did two of mine since my feral DPS was on the low side and I was willing to spare the Arctic Fur. As a druid I can take serious advantage of these buffs, since all three versions of the Fur Lining can be used by our different forms.
Another option would be to make the two leg armor kits, Jormungar and Nerubian in the 405-420 range. I didn't actually do this since the armor was selling for me, but you can try that if collecting the specialty scales is easier for you than the crystallized bits for the armor.
At 415 you might also be able to unlock some of the various bags that Leatherworkers can make, if you've been working on your factions. Kaliope was only level 72 when she got to this point, so the only bags she could learn were the Inscription one and the Dragonscale Ammo Pouch. The Pack of Endless Pockets wasn't working out as a money maker since many other LW were also grinding on it, and I didn't have the patience to farm 20 Icy Dragonscales for the ammo pouch. But again, if this is a workable option for you then go for it :)
You'll continue making the "Dark" armor pieces (or whatever) up to 420 skill at which point you'll be able to start purchasing wares from the Leather Vendor in Dalaran. This guy will let you buy recipes in exchange for Heavy Borean Leather and Arctic Fur. What I did here was buy one recipe at 420 skill and one recipe at 425, I'm too stingy to give him more than that! I tried to pick recipes that I thought would sell well and use ingredients I could easily farm. You can also stick with trainer recipes if you prefer, there are certainly plenty of those at 420. Just bear in mind that there's more competition from other LW on the auction, so purchasing a vendor recipe will probably give you an edge on selling your goodies.
At 425 you unlock another wave of recipes at the trainer and the vendor, so again try to focus on the items that you think will sell and are within your means to collect the materials. I relied quite heavily on my miner to provide Eternal Shadows, but you could always buy those off the auction pretty cheap. If you're not sure what gear will sell, either go with something you'd wear yourself or do a bit of research to see which LW items are popping up on druid/rogue/hunter pre-Naxx gear lists. It'll give you something constructive to do on your lunch break ;)
Unfortunately the 420 recipes are green by 430 and the 425 recipes are green by 435. So what to do? Well the only two recipes that stay yellow until 440 are the Frosthide Leg Armor and the Icescale Leg Armor. This is where you'll be happy you saved your Arctic Fur, because you need it to reach 440. You'll also need it after 440 for the epic recipes/items, but I assume you'll be happy to have that problem, heh. From 430-440 I made leg armor and amazingly I didn't have any missed skill points even though the recipes were yellow. I stocked enough mats for a dozen of them anyway, since I was anticipating some misses.
Since my skinning slave was only level 72 and couldn't go to a higher level zone, the easiest way I found to tackle this was to hit Howling Fjord and farm the Proto Drakes near Westguard for icy dragonscales (I also happen to prefer selling DPS kits vs Stam, but that's just me). If you're lucky, you haven't done the Proto Drake quest yet (Two Wrongs) and you'll be able to nab that nifty little frost wand they give you. The wand makes it much easier to tag the drakes, since my hunter had trouble getting in range of them even with range-boosting talents. I was able to get all my scales in about an hour or so, Wowhead lists the drop rate at about 13% for these guys. I managed to pick up a few Arctic Fur as well, but I already had a stash that I'd been saving anyway. All in all I felt this farming session was pretty reasonable for my last 5 points to 440.
I hope this information helps those of you who haven't leveled up your Leatherworking yet. I was pleasantly surprised that the last stretch wasn't as awful as I anticipated. If anyone has other tips to share on the Leatherworking grind, feel free to post it in the Comments!