The adage "cotton kills on the river" is a good tip to keep in mind. Cotton and other natural fibers, though great in hot, dry climates, serve to draw heat away from the body when wet. Synthetics, like polypropelene, polyester, or neoprene, are great fabrics because they dry quickly and offer a layer of insulation. Some synthetics, like fleece, will keep you warm, even when wet.
One of the difficulties of kayaking is that, unlike other sports, you are physically bonded to your kayak, meaning that layering clothing, which one might do in other sports like skiing, becomes a huge chore. One cannot remove a layer or add a layer quickly and efficiently while sitting in a kayak. Thus, plan ahead and know how you respond to different weather conditions. A quick roll can cool you off and a 5 minute steady paddle can warm you up.
Around the campsite, you want clothes that are warm in cool weather or cool on hot days. Synthetics are still the way to go. Quick-dry fabrics are available that are also bug-resistant. They have a weave that is so tight that mosquitoes and others cannot bite through. Light to heavy fleeces are great additions depending on the season. Long underwear can be a great addition in cooler weather and as pajamas - the best synthetics are comfortable and wick perspiration well. Wool socks are great for feet that have been damp or wet all day while paddling.
For more specific information on special types of clothings, see