There are several different kinds of paddles to choose from. It's important to select the right paddle for the right use. Here are some things to consider:
Paddle length greatly affects what you can do, and how effectively. Factors to consider for length are - style and shape of paddle blades - depth and width of kayak at the cockpit (relationship of seat height to cockpit depth) - body dimensions (torso and arm length) -desired paddling cadence
Again, blade shape directly affects what you will be able to do with your kayak. Some options include: plain flat, rectangles, spoon, bilateral symmetry, extended oval or modified oval, etc.
An unfeathered, or straight paddle, is one on which the blades both face the same direction in the same plane. A feathered, or offset paddle has one blade set at a 70 to 90 degree angle from the other, requiring movement of one hand to properly position the blades for paddling. There are debates on both sides of the issue of which is best.