The first thing to keep in mind is that you will likely not be able to paddle quickly. The harder you paddle, the more likely it is that you will steer yourself off course. Even if you usually think you do all the paddling when there is another person with you, it will soon become apparent that just their weight alone helps with steering and stability.
If you are sitting by yourself at the stern of the canoe, you will notice that the bow is no longer in the water. This means that it will only take the slightest bit of movement to turn the canoe. In order to paddle in a relatively straight line, you will have to correct your course with every paddle stroke.
An easy way to compensate for the missing person is to put some weight at the front of the boat. If you are going on a day trip, your lunch, shoes, fishing gear, your extra fleece and anything else you are bringing with you can all be stored at the front of the canoe. This extra weight will help the canoe to sit lower in the water and therefore stay in a straighter line when you're paddling. It may be helpful to think of the canoe as a seesaw; it works the best when both ends are evenly balanced.
If you are anticipating doing quite a bit of solo canoeing, it may be worth investing in a solo canoe. This canoe is designed specifically for the lone traveller and is balanced differently to a regular canoe. It is a little bit shorter than a standard two-person and the seat is much closer to the middle, which provides a better balance and easier navigation. These boats tend to be quite expensive because it is such a specialist market. A cheaper alternative is to use a kayak. They are longer and narrower than a canoe and benefits from a double paddle, all of which makes the boat much easier to steer.