congratulations, first and foremost... visit your local dive shop. if you got certified abroad, look for a local shop in the area you live. they will be able to customize a total dive system that will meet your needs. if you are on a limited budget, think about your rental gear and what you wished felt a little better and start with that item. always buy a little better and for the future. you may not think you'll ever do cold water diving, but a regulator that can dive in colder water is nice to have. buy a computer that can do nitrox and has the other features you like... (i.e. large screen, etc.)
comfort is the most important, so if you don't have your own thermal protection, in my opinion, is the best place to start. there is nothing like being warm and being in a great fitting wetsuit or drysuit. henderson "hyperstrech" is awesome! i like aqualung, apex, scubapro, and dive rite systems....
there is so many options that it's difficult to be more specific here, but you can email me...
cheers!
--carlos