First and foremost talk to the instructor who is teaching the class. While my tech instructor would do everything he could to make it easy for the diver there are some things that are just not gonna cut it with the majority of them. Poodle jackets or the so called "rec/tec" bc's are a no-no. Get a decent Back Plate and Wing set up. Hog Harness preferred. Things like a transpac are fine but simple is best. I advise my OW students to go this route if they plan on doing alot of diving and especially if they are going to travel. Packs small, easy to adjust, and fully customizable. There are "rec/tec" bcs out there that advertise that you can use doubles but really you can't. They are for the tech wannabe's who most likely wear them on caribbean dives and will never want to pick up a set of doubles let alone dive them.
It's like many of the people who buy Hummer H2s and 3s. They can't afford a real one, wouldn't know what to do with it they could, so they get this fancy looking thing and if you've ever looked at one they suck for cargo room, access to cargo and gear, and are too boxy looking. In the 60's and 70's they called em station wagons and they get used the same way today.
Regs should be envirosealed with straight hose setups- no swivels. Get an octo of equal quality to your primary. Slim-lines, swivels, low profile- forget em. And do not use console gauges. Wrist mounted with a basic brass and glass spg on the HP hose.
If you don't have a computer get one that will allow you to dive in gauge mode. You will not be relying on it for your dive plan. You'll be cutting tables and sticking to the plan as outlined. I use an Oceanic veo200 in gauge mode with an OMS bottom timer as backup. I am new enough to the tech scene to tell you what mistakes I made and did not make in getting gear set up. Fancy computers are pretty much overkill unless you are going for one that does mixed gasses including trimix.
Start diving doubles as soon as you can and get a good mentor along with an instructor. Work on your weighting and trim on shallow dives as much as you can. Get can light. You don't need a 50W HID right off the bat. A 10W HID or one of the new LED's ( I have a salvo 12W rebel) will work. Start adopting a Hogarthian attitude towards your diving in general. If I don;t need it- don;t take it. If I do have a back up or two.
Get a good quality reel or reels, primary, safety, and perhaps a spool or two. JJ's book is a good one but I'd also recommend Tom Mount's Exploration and Mixed Gas Diving Encyclopedia- The Tao of Underwater Survival. I use alot of the info in this book in my OW classes and especially in my AOW class. Talk to the instructor and find out what tables you'll be using. Get a copy of them or the computer program and get familiar with it. I use v-planner.
Stay away from all the little gimmicks out there. Your tech instructor will have an approved list of extra stuff he/she will allow you to use in class. You can customize things later once you find out and adopt the proper way to do so. Shiny and new, my buddy has one, or the lds says I need it is not a good reason. Is it going to enhance the safety of the dive, will I use it, is it truly necessary, is it a proven design, and will all the team members benefit or at least not be inconvenienced by it? THis is just part of choosing a new piece of gear.
I tell my AOW students that the reason they are taking the class is because they want to do dives that have the potential to get them into alot more trouble real fast. So slow and simple when changing setups. It's why I recommend the Hogarthian BPW setup to those who I think, or tell me they are going to do alot of diving. They soon find out bc's in general suck. Pockets are in the wrong place, stuff like gimmicky inflators just add to failure points and maintenance costs. Integrated weights are nice until you have to replace a pocket for one of these and realize that a 10 dollar weight belt, proper weighting, and good technique actually works better. And when doing tech dives especially with double steels chances are you won't need much weight if any.
If you have any other question drop a line or call. Info on my website-
www.udmaquatics.com