Today we had a comment on the blog asking for tips on what to do to benefit from the Cataclysm transition. I think the most important thing you can do is arm yourself with information and I've been posting everything I've learned in Beta to help you guys achieve that. Part of the transition process depends on your goals. If you're attempting a Realm First, you should be snatching up cheap WotLK materials for early skill points. If you're planning to power level a gathering profession, you need to clean out your bags/bank and get your gathering bonuses set up. Hopefully you're also staking out zones and perhaps even doing dry runs of the routes to prepare for the big day.
In terms of personal prep, buy whatever you need for yourself now, don't assume it will be there next week. Most players won't bother with buying and selling, they'll be too busy leveling and enjoying new content. So stock up on your consumables and buff items now. Better still, craft a bunch of consumables for other players and post them up for insane prices. There are always desperate procrastinators around to take advantage of :)
For those of you wanting to play the markets during this frenzy period, do your homework. Know what items have the strongest demand for leveling professions and be ready to grab them if you see a bargain price. Not only should you to be familiar with the leveling process for various professions, you probably also want to think ahead to the pre-raid crafting market. For example, in the first few days of WotLK arctic furs were selling for around 10 gold. They have never been that cheap since. But at the time, the average player had no idea what they were for and they dumped them. I was happily buying them at that price because I knew they were needed for epic recipes in Dalaran. The more you know about the big picture, the better you'll be at recognizing a good deal. I have my own theories about what items will be in demand, but each server economy is different. If you've done your homework, you'll be able to spot trends so you can take advantage of them.
In terms of general advice, my opinion is that Mining will be the biggest cash cow for the first week. Not only do you have three professions competing for your ores, you'll also be getting volatiles that are used by even more professions. Towards the end of Beta I was still farming ore just to beef up my volatile stash. Do not underestimate how important these will be for crafting. The only professions that don't use volatiles to level up are Enchanting and Jewelcrafting. Tailors need Water/Fire/Air, Engineers need Air/Earth/Fire, Smiths need Fire/Water/Earth, Scribes need all five types, and Leatherworkers need four of the five. If you can only focus on one area of crafting the first week for gold generation - make it Mining.
Feel free to share your thoughts and suggestions in the Comments area if you like, I'm sure I'm not the only one with opinions on this!