I've been trying really hard to level Cooking all the way to 450, but all the recipes are green at 440 and it's been very difficult to get the last 10 points. So I gave up and I'm just going to talk about getting to 440. Maybe Blizzard will ease the end-path before launch :)
The first thing I want to mention about Cooking is the daily quest in Dalaran. It will benefit you greatly to start doing these as soon as possible. Mostly because you'll want to start building up a stash of Dalaran Cooking tokens. The token recipes don't kick in until 400, but by the time you get there you'll want to have some buying power. In addition to the many new recipes you can get at 400 skill, the vendor also sells spices that you'll need to make those recipes. So take my advice - start early on Cooking dailies!
Getting to level 400 in Cooking is pretty easy, you get a whole slew of recipes at 350 from the trainer. The 350 recipes are yellow at 375 and go green at 382, but you can still get points up to 400 without too much trouble. From 382-395 I was still getting 50% skill-ups and from 395-400 I got about 25% skill-ups. Still, this was enough to reach the next wave of spells from the Cooking vendor in Dalaran.
Another suggestion I'd like to make is to plan a little for your Cooking progression once you start to collect the various meaty bits. It may seem kind of stupid, but there are certain types of meat you'll have much more of than others. Once you get to 400 and start looking at the Dalaran vendor's wares, you may be kicking yourself that you wasted your rhino meat on Rhino Dogs instead of saving them for the Small Feast. Some critter meats have a pretty low drop rate, so you don't want to waste them on easy skill-ups. But if you can plow your way up to 400 with the bountiful chilled meat and save the other vittles for later on, you'll thank me for the tip ;)
Once you reach 400, assess your meat (or fish) supply. Whatever you have the most of - buy a recipe for it. In my case this was Critter Bites, Northrend seems to be swimming in chilled meat. You're going to have to be selective with your recipe purchases unless you've accrued a bunch of Dalaran tokens. Once you've spent all your tokens it will take 3 days to collect enough for another recipe, so choose wisely!
Another thing you'll have to plan for is Northern Spices. They're required for every 400+ recipe and you can't just buy them. You usually get a few in the goodie bag (3-5 per bag?) from the daily quest, but not enough to level at a decent pace. The only way to get spices in any quantity is to purchase them with your Cooking tokens. So the token stockpiling becomes trickier because you also have to balance recipe acquisition with the spice purchases necessary to make those recipes. Now you begin to see why I suggest hitting town ASAP and working the Cooking daily even if you aren't ready yet.
I came up with a kind of workaround to this, maybe not ideal but it helps. At this point I've gotten 3 of my 4 toons portalled to Dalaran. So Kaliope does the cooking, she does the daily quest and purchases recipes with her tokens. She's also the keeper of piles of meat and fish (hehe). The other toons do the daily, but they purchase only spices with their tokens and send Kaliope all the spices they collect. The spices are not BoP, but the recipes are. So you can use your alts to funnel extra spices to your main 'chef' and help her progress faster. Obviously this doesn't help your alts with Cooking, but at least one of your toons is leveling up. Then once Kaliope caps, one of the other girls can be the recipe collector and the others can funnel spices.
Sooooo. The push to 450 is a bit... ugly. Well, it is right now anyway. I've submitted multiple "suggestions" about it and maybe it will be addressed before launch. At 415 cooking skill all of the 400 cooking recipes go green. You can still push your way to 425 with them, so no major worries there.
At 425 there are only 2 recipes: Gigantic Feast and Small Feast. The recipes are both yellow when you learn them and turn green at 437. Each feast requires 2x fishy + 2x some other fishy + 2x critter meat + 1x northern spice. The fish aren't too horrible to collect, just a bit time consuming is all. The critter meats in question are where it gets rough. Gigantic Feast requires 2x chunks o' mammoth while the Small Feast requires 2x rhino meat. Each of these meats has about a 15% drop rate. For the final 13 points (after the feasts are green), you'll be getting about 20% skill-ups for making them.
What this means is that just for the last 10 points of Cooking (not including what you make to get *to* 440), you'll have to make about 50 feasts. I put some numbers to this and came up with roughly 670 mammoths/rhinos that would have to be slaughtered for the meat. There's also 200 fish that would have to be caught and 50 spices that would have to be collected. This is probably about 8-10 hours worth of work. I've already spent about 3 hours collecting mammoth meat (and leather) and I'm still sitting at 441. Like I said... it's ugly.
Now I realize that there are no new recipes past 425 and I don't *have* to skill up to 450. But come on, of course we all want to! We're crafters, how can we hold our head high if we haven't maxed our professions?!?! Then we'll be like every other PvP scrub who can't afford his repair bills and is always mooching food and potions. Don't make us sink to that level, take pity on us! Ok, I'm done begging. The moral of the story is, getting all the recipes isn't too difficult. If you want to max out your Cooking skill, well I dunno what to tell ya. You will be Nesingwary's new best friend :P
UPDATE: This post was made during the BETA, please visit our updated version with new info!