Before you buy gear, and it is a good idea to dive it first if you can, define your purpose in diving so that you don't buy gear that you replace within a year.
For example, are you diving warm or cold water? That will to an extent determine your exposure suit and tank types. Will you be looking for long bottom times? If so that may determine computer types, i.e. Nitrox as well as air diving modes.
Will you dive year round? Might want either a 7mm wetsuit or drysuit depending on the warm/cold water reference above.
Will you be getting into wrecks or caves?
You can see that many of these basic things determine what you buy and to be honest I had no interest in wrecks until after 6 months of diving and some of what I bought will not work well in that environment and I purchased new to replace it.
I know what I want to do in diving now and my config reflects it, I've yet to get the certs for it and I will, but I wanted to get the proper gear first and then dive it to get used to it before I take the classes. You have enough workload in the class that the addition of diving unfamiliar gear is not a great idea.
Of course I had no idea this is what I wanted to do and just wanted to dive in the beginning. I did and had fun, but now I have an extra jacket style BC I don't use and I sold my AL 80's because I went steel. I didn't lose money on the deal, but you can see it took longer to get here.
So, define what you want first before you buy much gear. Consider the future in those purchases you make now, a Nitrox computer is a much better choice now as it will do most things you need.
Have fun and remember that those that own their own gear normally dive more often, rent what you don't have of course.
If you can dive it, find a DSS BP/W and try them out. Great rig, and of course there are many many others like it.
