You can paddle however is most comfortable for you, but efficiency is the name of the game...

Kayaking is supposed to be fun. If done incorrectly, though, you can seriously aggravate the muscles in your back, shoulders and chest. Before we get into kayaking techniques, lets speak first about posture. The most important thing you can do to ensure your kayaking adventure is physically enjoyable is to maintain good posture. If your kayak has a seat back (and most sit-ons do), make sure it is firm and supports your weight. Make all the necessary adjustments before you leave land, as adjusting seat straps is increasingly difficult when you are aleady sitting in the kayak.

For maximum efficiency, you should place your hands on the paddle a little wider than shoulder-width apart. The wider your hands are, the more power you can get per stroke, but place them too far apart, and you will begin to lose efficiency. Hold the paddle firmly, but don't squeeze too hard, or your hands will tire and blister.

Find your own rhythm, but use this as a guide

Forward/Reverse - Simply place the paddle in the water near your feet, with the blade perpendicular to the side of the kayak. Pull the blade through the water until it is even with your hip, and then lift the blade out and lower the opposite blade in on the other side. Simple? Not quite. The important thing here is that you pull the paddle through the water with your torso muscles, not your arms and shoulders. Your body should be swiveling with each stroke. If you maintain an upright posture, this will be far more comfortable in the long run - but you must fight the urge to pull with your arms and shoulders. When you do this stroke, make sure to keep the paddle as close to the kayak as possible, pulling it in as straight a line as possible. The more you arc your stroke, the more the kayak will turn, and the less progress you will make.

Turning - This stroke is essentially the same as the forward/reverse, with the exception that you want the blade to move in a wide arc, and not a straight line. The wider the arc, the more you will turn. Remember to start the stroke at your feet, and sweep all the way around to the rear of the kayak. Remember to maintain good posture, and turn with your torso. Shifting your weight in the direction you are turning also helps turn quickly, but it may lead to an inadvertent flip.

Sideways - Sometimes called a draw stroke, this maneuver is used for moving a kayak sideways (not an efficient way to travel, but sometimes necessary). Start with the paddle shaft extended out perpendicularly from the middle of the kayak. Place in the water with the blade paralell to the kayak. Pull it towards to you until the blade approaches the kayak. Now, turn the blade so it is perpendicular to the kayak and move it away from you. Then, repeat. Make sure your weight is centered and you are balanced before attempting this stroke, as it is quite easy to flip, especially in a narrow kayak.