How wide are your feet?
For narrow feet, Cressi 3000 LD are a great fin. Beuchat is another brand for narrow feet.
If you have medium feet, there is a wide selection available. Omer, Picasso, Dessault, and a bunch of others are all good choices. Most come with changable blades, so you can start with the basic plastic, and move up to fiberglass or carbon later if you want.
For really wide feet, imersion is the best choice I know of. I use them with 7 mm socks in Alaska, and have EE feet.
The carbon or fiberglass blades are definitely not a basic necessity, but rather something you try out later. The stiffness is much more important. Medium for most of us, soft for some, and stiff for those with really strong legs. For example, I am 6'/160 lb and have a pair of Picasso Black Teams that are way too stiff for me. I stay with medium stiffness plastic, fiberglass, or carbon blades, and all work well. A friend of the same height who weights about 325 lb has no problem with a similar pair of Picasso fins.
Another consideration is waqter temperature. Plastic blades get much stiffer in cold water.
There is an link to the results of some testing done by a multiple world record holder, Dave Mullins that I can't find at the moment. I think the title was "Cheap fins or expensive". I'll forward the link when I find it. Very informative, and most don't like the result. Dave stuck with plastic blades, because they fit well and he found no significant differrence in performance between plastic and carbon or fiberglass for 30 m dives.
