The Christmas holiday will be starting on Monday and it should be a good time. I enjoyed it last year and achievements will add too it hopefully. I decided to write a quick run down on some things you might want to have prepared before Monday to either save yourself money or even make some, for a more detailed guide check out this WoWInsider article.
A Frosty Shake and Scrooge require snowballs, which you can pick up in zones like Arathi Highlands. You will also be able to buy them off vendors now for just 10 copper. If you've been selling Snowballs on the AH, you probably want to get rid of them now because they won't be worth much anymore. Then again some people won't realise you can buy them from the vendor and maybe you'll still make some money.
The Winter Veil Gourmet is an interesting achievement for a few reasons. You'll need to cook all three of the Winter Veil recipes, so level your cooking to 325 if you are yet to get there. You can expect cooking materials to rise in price as people realise this. Two of the recipes also require Small Eggs. I've bought some very cheaply from the AH, and I'll resell the ones I don't need. You can probably make a tidy amount of money off this. There's also a way of making money off the vendors by making Hot Apple Cider. Check out the comments on WoWHead, an interesting discovery.
Let It Snow has potential to be a real pain, especially if your Alliance looking for a Orc Death Knight. I advice teaming up with a friend to create alts of the opposite faction although that will be limited to PvE realms. PvP players will have a bit more work to do, although I'm sure you can do it eventually hanging around Dalaran.
Fa-la-la-la-Ogri'la doesn't require Preserved Holly but there will still be a market for them. Although it's likely you can sell them for more during the year.
Tis' The Season is one you should really start saving for now. You'll need three parts of the Christmas outfit. The hat is available from Outland instances although they may update that. The clothes are made by tailors and the boots by leatherworkers. It's worth buying Runecloth, Wool, Rugged Leather and copper bar now, because the prices of these will be rising. If you're a leatherworker or tailor, you might want to start selling these now if you have the recipes from before or saving the materials if you hope to make some money after buying the recipe from Monday. If you have those materials, it's also better if you start selling them on monday at an inflated price. The good thing is both these pieces are not soulbound, so you can share them with your guild.
I'm really looking forward to this holiday. Most of the achievements are easy to get and won't get you frustrated. Hope everyone has a nice Winter Veil!