Wetsuits and other neoprene clothing work by holding a thin layer of water next to your skin where your body can warm it. To work best, a wetsuit should not have empty bulges or folds that will suck in chilly pockets of water when you swim, nor should it be so tight that it restricts breathing or motion.
Neoprene provides some padding against knocks and tumbles, and it provides some additional buoyancy (but by no means does it replace a PFD). Neoprene clothes are quite rugged and require little maintenance. In addition, they continue to provide considerable insulation (and buoyancy) even if torn.
Farmer Johns/Janes cover the torso and the full length of the legs, but not the arms. These are typically made in a 3mm neoprene and are used in moderate temperatures often in combination with a fleece top protected by a paddling jacket or drytop.
Shorty wetsuits are sleevless and short-legged. They are made with thinner (often 2mm) neoprene, and are used mostly in warm weather and water.
Useful features include rubber kneepads that protect the suit as you kneel to paddle or load your boat, and a zipper at the chest and ankles to assist dressing. Zippers should have neoprene backing flaps to prevent cold water surging through when you swim.
Neoprene is essentially rubber sponge insulation. It varies in quality. The bubbles in less expensive neoprene will collapse sooner in use, reducing the insulation value. Thicker neoprene suits provide more insulation but can inhibit freedom of movement. Thicker fabric (5mm) is generally used for covering extremities with items such as pogies or booties.
"Fuzzy rubber" is a general term for a newer generation of fabrics with rubber-like polyurethane outer surfaces and fleece inner faces. Because they stretch in all directions, fuzzy rubber garments can be cut to fit close without impeding movement. These pieces can be worn on their own in warmer conditions, or layered with other paddling wear when the air or water are colder.
Debate continues about whether fuzzy rubber on its own provides as much warmth as neoprene of equal thickness should you swim. However, since fuzzy rubber garments are usually more comfortable than neoprene, you may be more likely to be wearing them should you need them.
Both salt water and UV rays in sunlight can damage neoprene clothing. They should be rinsed after use and allowed to air dry. Turn gloves and boots inside out so that they dry completely. Store them in cool, dry, place. When it's time to wash your wetsuit, a soap specifically designed for neoprene will best remove dirt and odour without degrading the rubber.