When buying a board keep in mind:
Thicker and wider surfboards give you more floatation and stability. These boards tend to be a little heavier do to the added foam used.
Thin and narrower surfboards are more sensitive and maneuverable. These boards are light but are more suited for the experience surfers.
Mix up bottom contours and rail shapes to find that right board for you and your surfing style. Be your own person and pick a surfboard that suits you and not what you see the pro ride. Keep in mind pro surfers are surfing everyday, in many different conditions and have many boards shaped for their own styles. That since you will most likely not be having a dozen board quiver being delivered any time soon like the pros, you will want something that will satisfy a variety of wave conditions.
Another factor that is often overlooked by beginning and even amateur surfers is fin configuration and selection. There are everything from single fins, to twin fins, to traditional thrusters (2 side fins and a centered trailing fin), quads (four fins – two on each side and no center fin) and even quads for the ambitious and curious. Each configuration serves different purposes for different styles, conditions and needs and each serves different function. This is a really great guide to understanding your options with fin configurations: http://www.surfingguide.org/boardspecs/fins.php