Keep it Simple
You don't need a lot of equipment when fishing from a kayak, but many people load it down with extra items. A net, a rod and a tackle box are all you really need. Just put just a few tools inside your tackle box--a knife, pliers for emergency repairs, your lures and bait.
Certain types of kayaks have bulkheads, which keep them stable--even when water gets inside. If your kayak does not have a bulkhead, you'll need to find your own way of stabilizing it for fishing. Float bags are an excellent choice, because it's easy to install the bags. Try adding bags on the stern and another set along the bow.
If you find your kayak leaking water or notice any cracks on the side, you'll need to repair it. The best product for this situation is a substance called Marine Goop, which is available from most home improvement stores, including Lowe's and Home Depot. Simply apply the product to the cracks and let it dry overnight. It cures and shrinks to the spot, effectively sealing the area and making it completely waterproof.