Tips from Robert Clegg
Pace yourself. Don't let ego dictate your starting pace to more than you can handle. It is easier to increase your pace later with excess reserve energy. If you extend yourself too early your average pace will suffer. The only purpose for going hard at he start is to get onto the wave that you intend to ride for the day, or get through a restriction in the course before others.
Set realistic goals based on training pace. If they are too optimistic you are setting yourself up for failure and disappointment. This defeats he main goal and objective - to enjoy the sport. Often one forgets that completing the marathon course alone is an ACHIEVEMENT!
Keep your form. Rotate, rotate, rotate - use that excess strength in your torso, relax fingers on the forward moving hand.
Look at the big picture, it's quite simple. I have found many paddlers getting tunnel vision. Lift your head up, rotate, look around. Who is trying to catch you? Who is paddling with you and is looking strong or weak? Who is paddling to the side, are they losing or gaining ground and why? Looking at the nose of your boat and not around you will cost you simple advantages you could have capitalized on.
If you run into a head wind or the going gets tough, try gearing down. Move your hands further out and shorten your stroke. Try one or the other or both!
There's lots of advice out there to listen to, I would act on what makes sense - Paddle your own canoe!
HAVE FUN...