Kayak surfing is fun but it comes with a few conditions!
Just like a surfer, before jumping in the water for a "kayak surf session", you should observe the sea conditions: wave size, frequency, what side the waves are breaking on... Forget about launching if a red flag is flying and never overestimate your kayaking abilities.
Choose an inflatable kayak which, although a little slower at take-off on the wave, will prevent you from being injured if you collide with it.
Conditions looking good? Find the right waves: small to start with, and above all not too hollow, otherwise you will nosedive into the water... and you will find that not only will you have a lot of fun, but that it is great exercise too!
To catch your first wave, simply paddle hard when it comes up behind you. Then, when you feel the kayak take off on the wave, lean your upper body back to stop yourself from nosediving and use your paddle as rudder to try to follow the breaking wave... happy surfing and take care you don't cross the wave's path as it breaks and capsize!
Watch out for other users: the "waves + kayak" combination is dangerous for swimmers; surf far from bathing areas.